What grit diamond lapping compound do I need to get a mirror finish on agate?

For a mirror finish on agate, use a progressive sequence: 2,000-3,000 grit to remove grinding scratches, 8,000-10,000 grit for high-gloss polish, then 30,000-80,000 grit on a tin or felt lap for the final mirror surface.

How do I use diamond lapping compound to polish a knife blade to a mirror finish?

Start with 2,000-3,000 grit on a leather strop, progress to 8,000-10,000 grit for high-polish, and finish with 30,000-80,000 grit for a true mirror edge. Wipe clean between grit stages.

What is the difference between 5g and 50g diamond compound?

The 5g size ($6.00) is ideal for occasional use. The 50g size ($14.00) costs $0.28/g vs $1.20/g for 5g — over 4x more economical for regular use.

Can diamond lapping compound be used on tungsten carbide and hard metals?

Yes — diamond compound is hard enough to polish tungsten carbide (Mohs 9-9.5). Use 1,000-3,000 grit for pre-polish on a copper lap, then 10,000-30,000 grit for final mirror polish.

How do I apply diamond compound to a polishing lap without wasting it?

Apply a pea-sized amount with a toothpick or spatula, spread evenly, and work into the lap at low speed. Reapply only when polishing action slows — over-applying reduces effectiveness.

Collection: Diamond Compounds

Diamond Lapping Compound – Precision Graded Diamond Paste for Mirror-Quality Finishing

High-concentration diamond lapping compound with precisely graded diamond particles suspended in a balanced carrier medium. Delivers consistent, controlled polishing on gemstones, glass, marble, granite, tungsten carbide, stainless steel, and tool steel. Available in 5g ($6.00) and 50g ($14.00) sizes across 14 grit grades from 400 through 80,000.

🔥 Shop Diamond Lapping Compound – From $6.00

Available Sizes & Pricing

Size	Grit Range	Price	Cost per Gram
5g	400 – 80,000	$6.00	$1.20/g
50g	400 – 80,000	$14.00	$0.28/g — 4× more economical

Grit & Micron Guide

Grit	Particle Size	Stage	Application
400–800	~20–40 micron	Coarse lapping	Rapid stock removal, scratch elimination, surface flattening
1,000–1,500	~12–15 micron	Medium lapping	Intermediate scratch removal, surface refinement
2,000–3,000	~5–9 micron	Pre-polish	Fine scratch removal, surface preparation for polishing
5,000–8,000	~1–2 micron	Fine polish	High-gloss surface finishing
10,000–15,000	~0.3–0.5 micron	Ultra-fine polish	Near-mirror surface quality
30,000–80,000	0.1–0.2 micron	Mirror polish	Final mirror-quality polish on gemstones, carbide & steel

Compatible Surfaces

Gemstones: agate, jasper, quartz, sapphire, tourmaline, petrified wood (Mohs 5–9)
Hard metals: tungsten carbide (Mohs 9–9.5), tool steel, stainless steel, high-speed steel
Glass, optical components, marble, granite
Felt polishing pads, leather polishing discs, canvas polishing pads
Copper and tin laps for faceting; cloth buffing wheels for bench polisher applications

Related Tools

Felt Polishing Pads — Primary polishing surface for diamond compound on cabochons & flat laps
Leather Polishing Pads — Firm polishing surface for hard stone and carbide
Copper Flat Polishing Laps — Metal laps charged with diamond compound for faceting pre-polish
Tin Polishing Laps — Soft metal laps for final mirror polish stages with ultra-fine compound
Sintered Diamond Laps — Diamond laps for shaping before compound polishing sequence
Flat Lap Discs — Flat lap grinding discs used before switching to diamond compound

Frequently Asked Questions

Q: What grit diamond lapping compound do I need to get a mirror finish on agate?
A: For a mirror finish on agate (Mohs 7), use a progressive sequence: start with 2,000–3,000 grit on a leather or felt lap to remove fine grinding scratches, progress to 8,000–10,000 grit for high-gloss polish, then finish with 30,000–80,000 grit on a tin or felt lap for the final mirror surface. The ultra-fine 80,000 grit produces a water-clear mirror finish that showcases the stone's natural banding and color.
Q: How do I use diamond lapping compound to polish a knife blade to a mirror finish?
A: Start with 2,000–3,000 grit compound on a leather strop or felt pad to remove the finest scratches from the previous sharpening stage, then progress to 8,000–10,000 grit for a high-polish surface, and finish with 30,000–80,000 grit for a true mirror edge. Apply a tiny amount to the strop, work the blade in consistent strokes, and wipe clean between grit stages. Diamond compound produces a sharper, more refined edge than conventional sharpening compounds.
Q: What is the difference between 5g and 50g diamond compound — which should I buy?
A: The 5g size ($6.00) is ideal for trying a new grit, occasional use, or small projects. The 50g size ($14.00) offers a significantly lower per-gram cost ($0.28/g vs $1.20/g — over 4× more economical) and is the better value for regular lapidary polishing, faceting, or knife finishing where you use compound frequently.
Q: Can diamond lapping compound be used on tungsten carbide and hard metals?
A: Yes — diamond compound is one of the few abrasives hard enough to effectively polish tungsten carbide (Mohs 9–9.5) and other extremely hard metals. Use 1,000–3,000 grit on a cast iron or copper lap for carbide pre-polish, then 10,000–30,000 grit for final mirror polish. Also highly effective for polishing tool steel, stainless steel, and high-speed steel cutting tools.
Q: How do I apply diamond compound to a polishing lap without wasting it?
A: Apply sparingly — a small amount goes a long way. Use a toothpick or small spatula to apply a pea-sized amount to the lap surface, then spread evenly with your finger or a soft cloth. Work the compound into the lap at low speed before polishing. Reapply only when polishing action noticeably slows — over-applying reduces effectiveness by creating too thick a layer between the lap and stone.