Diamond drill bit buying guide
Updated: 2026-10-23
You are fitting a tap or a wall plug in a British bathroom, and the basket in front of you mixes a 6 mm wax bit with a 15-piece wet set. A diamond drill bit buying guide is only useful once the machine, the hole and the coolant are fixed. Star ratings do not rank those jobs against each other. Work through shank, diameter, bond and cooling in that order, then see where the eleven amazon.co.uk listings in the [diamond drill comparison](/hub/drilling-and-accessories/diamond-drill) sit. Prices below are the shelf prices saved on 19 October 2026. A qualifying purchase can earn a commission at no extra cost to you.
You are fitting a tap or a wall plug in a British bathroom, and the basket in front of you mixes a 6 mm wax bit with a 15-piece wet set.
You are fitting a tap or a wall plug in a British bathroom, and the basket in front of you mixes a 6 mm wax bit with a 15-piece wet set. A diamond drill bit buying guide is only useful once the machine, the hole and the coolant are fixed. Star ratings do not rank those jobs against each other. Work through shank, diameter, bond and cooling in that order, then see where the eleven amazon.co.uk listings in the diamond drill comparison sit. Prices below are the shelf prices saved on 19 October 2026. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Fit | Diameter | Bond | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  BRSCHNITT BRSCHNITT 32 mm M14 | M14 | 32 mm | Vacuum brazed | 9.0 | about £15.79 | View offer |
| Alternative |  DT-DIATOOL DT-DIATOOL five 6 mm M14 | M14 | 6 mm | Vacuum brazed | 9.0 | about £24.99 | View offer |
| Best value |  Meccion Meccion 22 mm pilot saw | Drill chuck | 22 mm | Diamond coated | 8.4 | about £9.69 | View offer |
On this page
Start with the machine you already own
An M14 thread screws onto a typical UK 115 mm or 125 mm angle grinder. A hex, round or triangular shank goes in a drill chuck. None of these boxes includes an adapter, and an adapter does not change the speed the listing states for the bit. In this sample the M14 rows are BRSCHNITT at £15.79, SHDIATOOL at £15.99 and DT-DIATOOL at £24.99. Hex rows are Zeeorymn, ColumPRO and Vearter. Round shanks are DKIBBITH and BGTEC. YUEDAHOMEE’s 65 mm saw is triangular. Meccion and Flintronic are chuck hole saws. Zeeorymn and DKIBBITH name angle grinders in the bullets while no adapter is listed. Vearter’s title mentions a grinder and the spec shank is hex. BRSCHNITT’s shank field says square and the bullets say M14, so plan for M14. If the machine is still undecided, settle it on the drill or angle grinder page before you chase a brand.
Measure the hole, then count the pieces
Sigma UK’s typical tap holes are 22 mm, 32 mm, 35 mm and 40 mm. Measure the fitting rather than guess from a product photo. Fixings are usually 6 mm to 12 mm. A 6 mm bit will not open a monobloc hole, and a 50 mm saw is the wrong tool for a wall plug.
Meccion is one 22 mm cutter at £9.69. BRSCHNITT is one 32 mm cutter. Flintronic’s fifteen pieces run from 8 mm to 50 mm at £10.99, and you may use one diameter and still have to water-cool every cut. Vearter steps through 20 mm, 35 mm and 50 mm, with 13 ratings, so the life is not established. ColumPRO’s unit-count field says 6 and the title says five. SHDIATOOL’s piece field says 20 and the title says two. Buy the number printed in the title. If two fields disagree, the Consumer Rights Act 2015 applies when the description you relied on is wrong.
Bond and cooling are one choice
A diamond-coated rim is usually one layer held in nickel. It wants water and a slow drill. Meccion states 500 to 800 rpm with water. Flintronic says water lubrication is required on hard materials. Vacuum-brazed bits are the usual dry-porcelain claim. The rows that state vacuum brazing are DKIBBITH, BRSCHNITT, SHDIATOOL, YUEDAHOMEE, Vearter, BGTEC and DT-DIATOOL. Small diameters are often wax-filled.
Wax cools the rim. It does not capture dust. None of these eleven listings is a named sintered bit such as Rubi DRYGRES. Zeeorymn and ColumPRO do not state vacuum brazing, so a dry-porcelain trade claim does not transfer. Topps Tiles puts dry grinder bits near 11,000 rpm and up to about 14,000 rpm. SHDIATOOL is more specific: 6,000 rpm recommended and 11,000 rpm maximum.
What the price bands can and cannot tell you
The entry band, about £6 to £11, is Zeeorymn at £5.99, ColumPRO at £9.49, Meccion at £9.69 and Flintronic at £10.99. UK reviews on packs under about £11 more often describe one or two holes and then a blunt rim. Meccion’s 815 reviews also include clean holes when water stays on the cutter, so the band is not one product. The mid band is about £13 to £19, including BRSCHNITT at £15.79. The upper end of this sample is BGTEC at £21.99 and DT-DIATOOL at £24.99. A 4.5-star line belongs to both a 32 mm M14 bit and a five-pack of 6 mm M14 bits. The stars are not a ranking of those two jobs.
YUEDAHOMEE has 18 reviews and Vearter has 13 ratings. Neither thin sample should decide the purchase. A review that mentions many holes is not a specification.
Common questions
What should I decide before the brand?
Decide the machine, then the hole diameter, then how the rim will be cooled. A brand comes after those three, because a 6 mm wax bit and a 50 mm wet saw can share a high star line and still be the wrong object for the fitting in your hand. If you already own only a drill, leave the M14 rows until you have a grinder.
What diameter do I need for a tap or a wall plug?
Measure the fitting. Sigma UK’s typical tap holes are 22 mm, 32 mm, 35 mm and 40 mm. Wall plugs and similar fixings are usually 6 mm to 12 mm. Meccion matches a 22 mm hole. BRSCHNITT matches a 32 mm hole. If your fitting is 35 mm or 40 mm, none of the single-size rows here is that diameter.
Wet electroplated set or wax-filled vacuum-brazed bit?
Choose the wet coated saw when you have a drill, a small number of holes, and you will keep water on the rim. Meccion and Flintronic are that shape. Choose a wax-filled vacuum-brazed bit when the listing states that bond and you can run it on the machine it names, usually an M14 grinder for the larger holes. Wax is a coolant. It is not a dust extractor.
Why do two fields on one listing disagree?
SHDIATOOL’s piece field says 20 and the title says two. ColumPRO’s unit count says 6 and the title says five. BRSCHNITT’s shank field says square and the bullets say M14. YUEDAHOMEE’s material field says glass and the bullets list tile. Use the title for the count and the diameter, and use M14 where the bullets and the grinder line say M14.
When is a 15-piece set the wrong buy?
Flintronic’s 8 mm to 50 mm set is the wrong buy when you have already measured one hole. You pay £10.99 for diameters you will not use, the listing requires water, and UK reviews often stop after a few holes. It is not a substitute for one vacuum-brazed M14 bit of the size you measured.
Related pages
Sources
Public UK sources from the research digest, last checked on 19 October 2026. Shelf prices and star lines are the amazon.co.uk figures in the display file.
- Topps Tiles: best drill bits for tiles (retrieved 19 October 2026)
- HSE CIS36: dust controls for drilling and coring (retrieved 19 October 2026)
- HSE CN8: diamond coring and slurry (retrieved 19 October 2026)
- ATS Diamond Tools: diamond drill bit types (retrieved 19 October 2026)
- Sigma UK: what size drill bit do I need (retrieved 19 October 2026)
- Würth UK: diamond dry core bit for tile, M14 (retrieved 19 October 2026)
- HSE: working with engineered stone (retrieved 19 October 2026)
- Tiling Supplies Direct: Rubi DRYGRES M14 bits (retrieved 19 October 2026)