How are grit/mesh/micron related and what is what?

Basically Grit, Mesh, and Micron are three different ways to measure particale size. In our case it is important because the size of the grit/polish that is being used defines the coarseness of the polish or cutting compound (laps too) that we are using to grind and or polish gemstones.

As you may know most diamond compounds/powders are sold in Grit sizes (100,000, 50,000...) in the USA.

Notice that there are some Grits that are listed that are the correct conversions, but are not commonly available for various reasons.

For example 60,000 Grit is the right number/conversion for 1/4 Micron, but you will almost never find 60,000 Grit available. The common Grit used is 50,000.

Note: In case you were wondering Alumina Oxide and Cerium Oxide are usually measured in Microns... Here is a link to polishes.

Note2: It is worth mentioning that just because a polish or compound says is it 14,000 Grit does not mean that it is all that size. It depends on the manufacturer and the method used to grade the compound. Some manufacturers use an average particale size and some use nothing "larger than" and so on. It also depends on the method used to actually "make" the polish/compounds. Read the labels or ask if you are not sure.

In general the more expensive brands do a better job of quality control and and sizing/grading of polishes and compounds. This is usually a case of you get what you pay for. Beware of very inexpensive polishes and compounds because they are usually not graded as well. It only takes one piece of grit the wrong size to scratch your stone and cause problems.

Grit - Mesh - Micron Conversion Chart

American Standard (Grit)	Mesh	Micron
100,000	0-0.5	1/4	Very fine and not used often commercially, mainly contest cutting or hobby cutters use it. It is seldom needed.
60,000	0-1	1/2	This is seldom used. 50,000 Grit is really what is used, and quite common for polishing Sapphire and other hard materials. You will need it.
14,000	0-2	1	This is the standard commercial polish for Sapphires, although I recommend going another step to 50,000. You will need it.
13,000	1-2	1.5	This is seldom used because it is so close to 14,000...
9,000	2-3	2.5	This is seldom used because it is so close to 8,000...
8,000	2-4	3	This is my standard pre-polish for Sapphires and other hard materials. You will need it.
5,000	2-6	4	This is seldom used.
4,500	4-6	5	This is seldom used.
2,800	5-10	7	This is seldom used. 3,000 is the standard what you will commonly find. You will need it.
1,800	6-12	9	This is seldom used.
1,400	8-20	14	This is seldom used.
1,200	10-20	15	This is seldom used.
1,050	12-25	18	This is seldom used.
800	20-30	25	This is seldom used.
600	20-40	30	This is a common grit and people often charge copper laps with it. I prefer plated laps.
500	30-40	35	This is seldom used.
325	40-50	45	This is a common grit and people often charge copper laps with it. I prefer plated laps.
285	50-60	55	This is seldom used.
240	60-80	70	This is seldom used. 260 is the common grit and people often charge copper laps with it. I prefer plated laps.
225	80-100	90	This is a common grit and people often charge copper laps with it. I prefer plated laps.
160	100-120	110	This is seldom used.
100	120-160	150	This is a common grit and people often charge copper laps with it. I prefer plated laps.

 

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