Choose the Right Granite-Drilling Setup Before You Touch the Stone

A diamond bit for granite is not a universal product. The correct setup depends on the finished hole diameter, total material thickness, drilling method, available tool, connection type, and permitted operating speed.

For most new faucet, plumbing, or conduit openings, start with a diamond core bit or diamond hole saw explicitly rated for granite. A small fixture or anchor hole may suit a granite-rated diamond-tipped bit. Milling and tolerance tools are normally for enlarging or shaping an existing opening unless their manufacturer expressly permits them to start holes.

The diamond label alone is not enough. A bit with the correct nominal diameter can still be unsuitable if its barrel is too shallow, its connection does not match the tool, or its cooling requirements cannot be met safely.

The short answer: which diamond bit drills granite?

For a new, relatively large hole in granite, buy a granite-rated diamond core bit or diamond hole saw in the diameter required by the fixture. For a small hole, consider an appropriately sized diamond-tipped bit whose manufacturer specifically lists granite as a compatible material.

Manufacturer guidance generally makes the same distinction between diamond-tipped bits for smaller holes and core hole saws for larger openings. It also warns that carbide masonry bits intended for brick or concrete may dull quickly or fail in granite (Johnson Tools’ granite-drilling guide).

A core bit is a hollow cylinder with diamond-bearing material at its cutting edge. It abrades a narrow circular ring rather than grinding away the entire hole area. That leaves a center core, or slug, which separates when the bit passes through the stone. Because only the ring is removed, a core bit abrades less granite than a solid bit with the same outside diameter.

Keep these categories separate:

• Core bit or diamond hole saw: Produces a circular opening and leaves a center slug.
• Solid diamond-tipped bit: Removes material across its full diameter and is generally considered for smaller holes.
• Milling bit, finger bit, or tolerance tool: Primarily enlarges, corrects, or shapes an opening.
• Non-coring bit: Removes material without leaving the same kind of center slug.
• Masonry bit: Usually a carbide-tipped, impact-oriented tool for brick, block, or concrete—not the default choice for polished granite.

For a broader overview of how common drill-bit types match different materials, remember that retail categories do not establish operational compatibility. A product shown under a granite filter might be a milling tool rather than a hole-starting tool. Confirm its intended use in the documentation for the selected product.

There is also no defensible universal “best” granite bit. Retail placement, ratings, sales volume, and labels such as premium or professional are not comparative performance tests. Choose from documented specifications first.

Use this six-point checklist to choose the bit

Begin with the object that must pass through the granite. The installation drawing for the faucet, anchor, pipe, conduit, dispenser, cable gland, or other fixture should control the finished diameter.

A 1-3/8-inch or 35 mm opening is commonly cited for faucet installations, but it is not correct for every faucet. The fixture manufacturer’s specified cutout or permitted range takes priority (Dynamic Stone Tools’ selection guide).

Check these six points:

1. Finished diameter
2. Total drilling depth
3. Bit format
4. Wet-or-dry rating
5. Tool interface
6. Permitted operating speed

Finished hole	Typical application	Suggested bit format	Required workable depth	Wet-or-dry rating	Tool interface to verify
Small, fixture-specified hole	Anchor, hardware, or cable opening	Granite-rated solid diamond-tipped bit or small hole saw	Greater than every layer to be penetrated	Must match the planned method	Straight or suitable hex shank for a compatible chuck
Medium circular opening	Supply line, dispenser, pipe, or conduit	Granite-rated core bit or hole saw	Greater than the total assembly thickness	Wet, dry, or explicitly dual-rated	Chuck-compatible shank or matching threaded spindle
Faucet opening	Faucet or accessory mounting	Granite-rated core bit in the fixture-specified diameter	Greater than the slab and attached substrate	Select before purchase	Product-specific shank or thread
Large penetration	Plumbing, conduit, or custom fixture	Granite-rated core bit designed for the diameter and workload	Must clear all layers and allow slug management	Confirm before buying	Matching core machine, grinder, drill, or approved adapter
Existing hole requiring correction	Minor enlargement or shaping	Manufacturer-approved milling or enlarging bit	Sufficient for the edge being modified	Product-specific	Product-specific
Deep or repeated hole	Fabrication or production work	Deeper segmented or laser-welded core bit offered for granite	Greater than the full drilling depth	Chosen for the work environment and duty	Compatible dedicated or handheld equipment

1. Establish the actual finished diameter

Do not select a bit by appearance or by measuring only the outside diameter of a pipe. Mounting hardware may require clearance, while a flange may cover an opening larger than the fitting itself. Determine whether the installation drawing gives an exact diameter, a permitted range, or minimum clearance.

Treat nominal marketplace sizes cautiously. One five-pack listing marketed for granite calls the selected bit both 12 mm and 1/2 inch, while its product table reports a 12.7 mm cutting diameter and warns that the resulting hole may be slightly smaller. Because one-half inch equals 12.7 mm, those descriptions are not interchangeable where tolerance matters (Newsfana marketplace listing).

A conflicting listing is not a verified dimension. Obtain a dimensioned first-party specification or test the actual bit on representative scrap before drilling the workpiece.

2. Measure every layer in the drilling path

Possible layers include mesh, plywood, mortar, substrate, or reinforcement.

Overall bit length is not the same as workable depth. The shank, thread, closed end, or internal geometry may consume part of the listed length.

3. Select the format for the operation

Use a core bit or hole saw for a new circular opening when its documentation permits that operation. Use a solid diamond-tipped bit for a suitably small opening. Reserve milling, finger, and tolerance tools for enlargement or shaping unless their manufacturer expressly authorizes hole starting.

4. Decide between wet and dry before purchasing

A wet-only bit is unsuitable where water cannot be supplied and contained using an appropriate system. Dry work requires a dry-rated bit and a plan for cooling pauses and dust control. If a product is advertised for both methods, verify that the dual rating applies to the selected diameter rather than only to the broader product family.

5. Match the connection exactly

Straight and suitable hex shanks may fit compatible drill chucks. Threaded fittings such as 5/8-inch-11 and M14, along with CNC and specialty connections, require a matching spindle, holder, or manufacturer-approved adapter. Specialist granite-core-bit catalogs list these as distinct connection systems rather than interchangeable fittings (Diamond Tool Store’s granite core-bit catalog).

Never infer compatibility from a photograph. A threaded angle-grinder bit does not fit an ordinary drill chuck merely because both tools rotate. Connection specifications can also vary by diameter within one product range.

6. Match the speed requirement

Check the manufacturer’s permitted or recommended RPM for the exact bit diameter, material, and wet-or-dry method. Then confirm that the tool can maintain a controllable speed within that range.

Final pre-purchase check:

• Granite is explicitly listed as compatible.
• The diameter matches the fixture specification.
• Every layer in the drilling path has been measured.
• Workable depth exceeds the required drilling depth.
• The bit is rated for the planned wet or dry method.
• The selected diameter has the required shank or thread.
• The tool can operate within the permitted RPM range.
• Current operating instructions are available.
• The guide, cooling, slurry, or dust-control accessories fit the complete system.

Core, coated, brazed, and segmented bits are not the same

“Diamond bit” describes a broad tool family. Construction affects how abrasive is retained, how heat and debris are managed, and whether new diamond can become exposed as the working edge wears. Construction alone does not identify the best bit for every granite job.

Hollow core bits

A hollow core bit grinds a circular kerf and leaves a center slug. Its cutting edge may use a continuous abrasive rim, separate segments, slots, or perforations. Core bits are commonly considered for faucet and plumbing openings because they remove less stone than a solid tool of the same outside diameter.

Solid diamond-tipped bits

A solid bit removes material across the full hole diameter. It can be useful for small holes where a hollow core would be impractical. The term diamond-tipped does not establish granite compatibility, drilling depth, speed, connection, or cooling requirements.

Electroplated or diamond-coated bits

An electroplated bit has a single diamond-bearing layer, commonly bonded with nickel. Once that layer wears away, the bit must be replaced. These products can be candidates for occasional or limited work if their diameter, depth, material rating, and instructions fit the job.

A low price does not prove that a coated bit is disposable, nor does it guarantee completion of a particular hole. Stone, depth, speed, pressure, cooling, alignment, and debris removal all affect wear.

Vacuum-brazed bits

They are sold in core and other tool formats. Do not assume that every vacuum-brazed product has the same cooling method, usable depth, connection, or starting technique.

Sintered or segmented core bits

Sintered tools contain diamond-bearing material through multiple layers of the working segment rather than only in a single surface coating. As the bond wears, more diamond may become exposed.

Some sintered tools can be dressed, but dressing permission and procedure are product-specific. A vendor guide distinguishes single-layer electroplated tools from multilayer sintered tools and says bit life varies with speed, lubrication, pressure, and material density (Eternal Tools’ diamond-bit guide).

Do not push a slow-cutting bit through a cinder block, dressing stick, or other abrasive unless the selected bit manufacturer authorizes that material and procedure.

Thin-wall and standard-wall core bits

A thin-wall core bit removes a narrower ring of granite. A standard-wall design has a more substantial barrel or cutting structure and is commonly positioned for repeated work. These are design choices, not universal guarantees of speed, service life, accuracy, or edge quality.

A narrower kerf reduces the volume of granite removed, but practical performance still depends on segment design, stone, machine stability, alignment, speed, and cooling. Without controlled head-to-head testing, categorical claims that one construction is faster or longer-lasting are unsupported.

Retail catalogs separately classify wet core bits, dry core bits, vacuum-brazed tools, non-coring bits, milling tools, and CNC tooling. That separation reinforces the central buying rule: these categories are not automatically interchangeable merely because they use diamond abrasive.

Wet versus dry drilling: choose the method before the bit

Commercial stone-tool guidance generally favors wet drilling. Water can cool the stone and diamond-bearing edge, carry ground material out of the kerf, and suppress much of the dust generated at the cut. Dry drilling remains useful where controlled water use is impractical, but it requires a bit expressly rated for dry granite drilling.

Wet-rated and dry-rated bits must not be assumed interchangeable. Supply water as directed for a wet-only bit. For dry work, use the cooling and duty cycle stated for the selected dry-rated product.

Consideration	Wet drilling	Dry drilling
Cooling	Water cools the interface when delivered correctly	Managed through dry-bit design, intermittent drilling, and cooling pauses
Debris	Ground stone leaves as slurry	Debris becomes captured or airborne dust
Portability	Requires controlled water delivery and containment	Useful where supplying water is impractical
Housekeeping	Slurry must be contained	Dust must be captured and cleaned without unnecessary redistribution
Electrical concerns	Equipment, connections, and work methods must suit the wet environment	No intentional water, but normal electrical and tool-safety requirements remain
Workload	Commonly chosen for thick material and repeated work	Often selected for portable or limited work where the bit permits it
Bit selection	Wet-rated or expressly dual-rated	Dry-rated or expressly dual-rated

Dry drilling is not simply wet drilling without water. One commercial stone-tool guide gives 10- to 15-second passes followed by cooling pauses as an example for dry work, but the cycle is not universal and does not replace the instructions for the selected bit (Dynamic Stone Tools’ wet-and-dry guidance).

Insufficient cooling, excessive speed, excessive pressure, or trapped debris can contribute to overheating, glazing, slower cutting, and premature wear. Wet drilling can also perform poorly if water does not reach the cutting interface or slurry remains packed in the kerf.

Dry granite drilling can generate silica-containing dust, which commercial stone guidance identifies as a serious respiratory hazard. The available sources do not establish a universal vacuum specification, respirator, exposure limit, or compliance procedure. Follow the tool and dust-control manufacturers’ instructions and the occupational-safety requirements applicable to the work location.

Match the bit to the drill, grinder, or core machine

Compatibility depends on the connection, permitted speed, tool type, and cooling or dust-control system. The word diamond does not make a bit universally compatible with handheld drills, angle grinders, drill presses, dedicated core machines, or CNC equipment.

Use this interface map as a preliminary screen:

• Straight shank: May fit a drill chuck if the shank falls within its capacity.
• Suitable hex shank: May fit a compatible conventional or quick-change chuck.
• Threaded core bit: Requires a matching spindle or an approved adapter system.
• CNC or specialty fitting: Requires the specified holder, spindle, machine, and coolant arrangement.
• Pilot or guide system: Must match both the bit and the power tool.

The Brute S-43AX illustrates the kind of seller-reported specification that should appear in a useful listing. Its retailer markets it for granite and quartz, wet or dry operation, with a 5/8-inch-11 fitting, 3-inch usable depth, and selectable diameters from 3/16 inch through 6 inches (Brute S-43AX product page). Those specifications do not prove cutting speed, accuracy, service life, or compatibility with every tool carrying the same thread.

Marketplace listings can be less consistent. One ORIXTREME variant is marketed as a dry 20 mm angle-grinder bit with a 5/8-inch-11 thread and 75 mm workable depth, yet the same page also uses “4/5 inch” and “0.75 inch” size descriptions that do not agree precisely with one another (ORIXTREME marketplace listing). Treat these as seller-reported values until confirmed for the selected variant.

The available evidence does not establish a universal minimum wattage or torque. Instead, confirm:

• The exact connection for the selected diameter
• The bit’s permitted RPM
• The tool’s controllable speed under load
• The tool types authorized by the bit manufacturer
• Compatibility with the cooling or dust-control attachment
• The ability to guide the machine squarely through the required depth

A controlled technique for starting and completing the hole

The following sequence is a planning framework, not a substitute for the selected bit and tool manuals.

1. Confirm the hole before setup

Check the center location, finished diameter, permitted tolerance, and total depth. Confirm that the fixture flange will cover the specified opening without relying on it to hide a badly misplaced hole.

For installed stone, inspect the area above and below the drilling point. Determine whether the slug could strike cabinetry, plumbing, wiring, an appliance, or a finished surface.

2. Support and secure the stone

Loose granite should be supported on a stable surface, especially around the intended opening, and secured against movement. Do not hold a small workpiece by hand while drilling it.

An installed countertop requires a site-specific assessment for seams, repairs, cutouts, backing, and unsupported areas. Manufacturer guidance also emphasizes firm support, low starting speed, light pressure, and water cooling where required (Johnson Tools’ operating guidance).

3. Establish a guiding method

Depending on the product, anti-wander methods may include:

• A secured template or guide jig
• A compatible pilot-bit or pilot-pin system
• An appropriately made starter divot
• A manufacturer-approved angled start that establishes part of the cutting ring before the tool is brought upright

A pilot hole is not mandatory for every core bit. Use the starting method authorized for the particular bit and machine.

4. Start slowly and establish the ring

Position the bit accurately and begin at low speed. Allow the abrasive edge to establish a stable circular track before increasing to the specified operating speed or bringing an angled bit into final alignment.

If the tool starts to skate, stop and correct the guide, alignment, or starting method. Do not compensate by increasing speed or pressure.

5. Maintain alignment and moderate pressure

Keep the bit on the intended axis and use light-to-moderate, steady feed pressure.

Maintain the required cooling or dust-control system throughout the cut. For wet work, water must reach the cutting interface rather than merely wetting the surrounding surface.

6. Manage debris during deeper drilling

For deeper wet holes, periodically withdrawing the rotating bit may improve water circulation and help release slurry. A commercial guide specifically applies that recommendation to holes deeper than 2 inches, but the selected manufacturer’s procedure controls (Dynamic Stone Tools’ drilling guidance).

7. Ease off near breakthrough

Reduce feed pressure substantially as the bit approaches the underside. The remaining granite is thin and more vulnerable to exit-side chipping.

Where both faces are accessible and reliable alignment is possible, drilling partway from each side can limit exit damage. Poor alignment, however, can leave a stepped or oversized opening.

8. Use the manufacturer’s speed

There is no universal granite-drilling RPM. Speed depends on diameter, construction, cooling method, stone, and machine.

Commercial guidance gives 600–900 RPM for wet drilling a 1-3/8-inch granite hole, but that is an example for one diameter and method—not a general speed for diamond bits.

Use rotary-only operation unless the selected bit-and-stone system expressly requires otherwise. Commercial manufacturer guidance warns that hammer action may contribute to cracking or chipping in brittle granite. Contrary forum reports are anecdotes, not controlled evidence.

Safety checks for wet work, dry work, and installed countertops

Granite drilling combines rotating machinery with either water and slurry or airborne dust. The available evidence identifies important hazards but does not establish a complete, jurisdiction-specific safety procedure. Use the exact tool, bit, accessory, and dust-control manuals and comply with applicable workplace requirements.

Do not combine wet and dry controls casually. Adding improvised water around a dry-only electrical tool, or disabling dust capture because the surface is damp, can create a different hazard rather than solving the original one.

Wet-work precautions

A commercial wet-core guide recommends equipment appropriate to wet work, grounding where the equipment design requires it, GFCI protection, wet-rated extension cords where applicable, controlled water delivery, avoidance of standing water, eye protection, non-slip footwear, workpiece security, and keeping bystanders clear (Drill Bit Warehouse wet-core safety guide).

That retailer guidance is not a complete electrical-safety standard. In particular, GFCI protection does not make a dry-only tool, damaged cord, unsuitable connection, or improvised wet method acceptable. Keep water and slurry controlled, and use only equipment and accessories authorized for the intended environment.

Dry-work precautions

Dry work requires a bit expressly rated for dry granite drilling and a compatible source-capture system.

The supplied commercial evidence does not establish one vacuum class, shroud, respirator, cleanup method, or exposure-control program for every tool and jurisdiction. Follow applicable occupational requirements and the instructions for the complete drilling and capture system.

Physical controls for either method

Use eye protection and non-slip footwear as directed by the governing equipment instructions.

Glove use should follow the specific machine and task instructions.

Stop-and-check questions for an installed countertop

Before drilling installed granite, ask:

• Is plumbing or wiring hidden below the proposed center?
• Will the bit enter a cabinet rail, drawer, appliance, sink component, or wall?
• Is there plywood, mesh, mortar, reinforcement, or another backing layer?
• Is the hole near a seam, repair, crack, edge, sink cutout, or unsupported span?
• Can the underside be inspected and accessed?
• Where will the water, slurry, dust, and center slug go?
• Could drilling affect countertop, installation, fixture, tool, or bit warranty terms?
• Can the stone be supported without damaging cabinetry or finishes?
• Has the material been confirmed as granite?

These are site-assessment questions, not universal clearance rules. Installation details vary.

Consider hiring a qualified stone fabricator when the slab is valuable and installed, the substrate is uncertain, the underside is inaccessible, the proposed opening is near an edge or seam, hidden reinforcement or utilities may be present, or irreversible damage would be unacceptable.

Troubleshoot wandering, slow cutting, glazing, and chipped exits

Stop and diagnose the setup rather than responding to every problem with more pressure.

Symptom	Possible causes	Response
Bit skates or wanders	Loose guide, excessive starting speed, tilted tool, unsuitable starting method	Stop, secure or reposition the guide, reduce starting speed, and use an approved method
Cutting becomes slow	Glazing, inadequate cooling, compacted slurry, wrong RPM, worn abrasive, wrong material rating	Check cooling and debris removal, confirm speed and compatibility, and inspect the cutting edge
Bit or stone overheats	Excessive speed or pressure, insufficient water, long dry passes, blocked kerf	Stop, allow cooling, restore the specified method, reduce feed, and clear debris
Cutting edge looks smooth	Bond has glazed and diamond exposure has fallen	Correct speed, pressure, cooling, and debris removal; dress only if authorized
Bit wears rapidly	Wrong granite rating, wet bit run dry, excessive speed or pressure, poor cooling	Recheck material and method, restore cooling, and operate within specified limits
Entry is jagged	Movement during startup, inaccurate guide, excessive initial speed or pressure	Improve guidance and establish the cutting ring gradually
Exit side chips	High feed near breakthrough, poor support, changed alignment	Reduce pressure near exit, improve support, or consider an accurately aligned two-sided cut

If segments remain visible but performance has declined, the bit may be glazed rather than exhausted. Excessive speed or pressure, inadequate cooling, and poor debris removal can all contribute. Correct the operating cause before attempting to expose fresh diamond.

Some sintered bits can be dressed, but permission is product-specific. Do not use a cinder block, dressing stick, or other abrasive merely because generic guidance mentions it.

Rapid wear calls for a full setup review:

• Confirm the bit is rated for granite.
• Verify that a wet-only bit was not operated dry.
• Check that water reaches the cutting interface where required.
• Confirm that dry passes follow the selected instructions.
• Verify RPM for the diameter.
• Use moderate feed pressure.
• Remove slurry or dust effectively.
• Check whether poor alignment is making the barrel rub.
• Identify any unanticipated backing or reinforcement.

Bit life cannot responsibly be promised as a fixed number of holes. It varies with stone, diameter, depth, speed, pressure, cooling, alignment, and technique.

Buying examples by job, not by unsupported rankings

Use the job profile to narrow the category, then compare documented specifications rather than superlatives.

Occasional small-hole DIY job

For one or a few small holes, compare granite-rated solid diamond-tipped bits with small coated diamond hole saws. Verify the diameter, shank, workable depth, wet-or-dry requirement, speed instructions, and starting method.

An inexpensive coated set may be reasonable for limited work, but price and bit count do not establish whether it will complete the intended hole. The Newsfana five-pack discussed earlier is marketed for granite yet uses inconsistent 12 mm, 12.7 mm, and 1/2-inch descriptions (Newsfana product page). Where tolerance matters, obtain a first-party dimension or test the actual bit on representative scrap.

Portable countertop-installation job

Where controlled water use is impractical, compare only dry-rated bits that match the available tool. Check:

• Exact spindle or shank
• Diameter-specific connection
• Permitted RPM
• Workable depth
• Authorized starting method
• Cooling-pause instructions
• Dust-capture compatibility
• Consistency between the listing, packaging, and first-party documentation

A dry-rated angle-grinder bit is not necessarily compatible with a drill. A straight-shank hole saw may fit a drill chuck but may not be rated for grinder speed. Portability does not remove the need for stable guidance or dust control.

Repeated fabrication or deep-hole work

For repeated or deeper drilling, compare segmented, sintered, or laser-welded core bits by:

• Documented diameter
• Usable drilling depth
• Segment construction
• Connection
• Wet, dry, or dual rating
• Diameter-specific RPM
• Authorized machine types
• Slurry-removal features
• Manufacturer-approved maintenance procedure

Retail listings show that granite-rated core bits are available across a broad diameter range, including a 1-3/4-inch brazed core bit or hole saw marketed for granite (Home Depot’s Monster BDBP0134 listing). Diameter availability alone says nothing about thread, depth, speed, cooling method, or machine compatibility.

Apply evidence labels carefully:

• Seller-reported specification: A diameter, thread, depth, or material rating stated on a listing.
• First-party specification: A value confirmed in current documentation from the product manufacturer.
• Independent measurement: A dimension or result measured under a disclosed method.
• Performance claim: Words such as faster, smoother, durable, or professional without comparative testing.
• Customer rating: Aggregated buyer feedback, not a controlled granite test.
• Anecdote: One user’s outcome under incompletely documented conditions.
• Independent test result: A controlled comparison that identifies the stone, machine, method, speed, depth, and measured outcomes.

The available evidence does not provide controlled comparisons of cutting time, temperature, hole accuracy, edge chipping, wear, or completed holes. A named-product ranking would therefore be unsupported.

Frequently asked questions

Can I use a regular drill with a diamond bit for granite?

Possibly. The bit must have a straight or suitable hex shank that fits the chuck, the drill must provide a controllable speed within the permitted range, and the bit manufacturer must authorize that tool type.

A threaded core bit does not directly fit a standard drill chuck. An adapter is appropriate only when approved for the complete system and compatible with its speed, cooling, guarding, and load. There is no evidence-based rule that every household drill is either sufficient or insufficient for every granite hole.

Should I use hammer mode when drilling granite?

Generally, no. Use rotary-only operation unless the selected bit-and-stone system expressly requires another mode. Commercial manufacturer guidance warns that impact can contribute to cracking or chipping in brittle granite.

Forum advice is conflicting, and reported outcomes include broken and scratched granite tiles. Such anecdotes should not override the selected manufacturer’s instructions.

What size diamond core bit is used for a faucet hole?

A 1-3/8-inch or 35 mm core bit is commonly cited for faucet openings, but it is not a universal faucet-hole size. Check the installation guide for the exact faucet or accessory and use its stated diameter or permitted range (Dynamic Stone Tools’ faucet-hole guidance).

Also confirm that the workable depth exceeds the granite and every backing layer to be penetrated.

Can the same diamond bit drill granite wet and dry?

Only if the manufacturer explicitly rates the exact product and selected size for both methods. Some core bits are dual-rated; others are wet-only or dry-only.

A wet-only bit should receive its specified water supply. Dry operation requires a dry-rated design, the prescribed cooling cycle, and compatible dust capture. Do not infer dual use from appearance or from another diameter in the same product family.

Why has my diamond core bit stopped cutting?

The bit may be glazed, overheated, clogged with slurry, running at the wrong speed, receiving inadequate cooling, or lacking sufficient exposed diamond. It may also be worn out or unsuitable for granite.

Stop and check the material rating, RPM, feed pressure, cooling method, debris removal, alignment, and segment condition. Some sintered bits can be dressed, but only by the procedure authorized for the selected product.

Final decision rule: Identify the required finished hole and total drilling depth first. Choose a granite-rated bit format intended for that operation, match its connection and speed range to the tool, and follow its wet-or-dry instructions. Controlled alignment, suitable cooling or dust capture, moderate pressure, and a gentle breakthrough matter as much as the diamond label. If an installed slab is valuable, poorly supported, near an edge or seam, or may conceal utilities or reinforcement, pause and consult a qualified stone fabricator.