Friable Diamond Polish

Jeff R Graham shares his opinions and thoughts on various topics in Just Ask Jeff. See what his answers are to What are Friable diamonds Polishes?

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Friable Diamond Polish

I am sure that many people have see the phrase "friable" some where on a package of diamond polish.


When you spend the money to buy friable diamond polishes. You are buying a specific type of diamond crystal. Friable diamond polishes usually costs a little more, and are well worth it, depending on your application.

What does "friable" mean? There are many types of crystals and we all know there are many types of diamond polishes. Basically a friable crystal is a long narrow crystal designed to break up as it is used.

What you are essentially getting and paying for is a particular type and shape of diamond crystal (see below) that is designed to break down during the cutting/polishing process in such a way that not only will the diamond polishing crystals become finer but they will also remain sharp through out the cutting and polishing process. These types of polishes stay sharp because as the crystals break the edges stay sharp and continue to polish.

But keep in mind that friable diamond polishes work best for fine grits and polishing. Friable polishes also work best on hard laps like ceramic, and composite laps. The reason for this is because friable diamond crystals are designed to "break down" during use and become finer. So these types of crystals will break down best on a hard surface lap. On a hard surface laps the friable crystals will not dig into and become buried in the soft metal of the lap, like a tin lap. Friable polishes work fine on softer laps, it is just that they will tend to imbed in the softer laps and not break down as much as they will on a hard surface lap that they will not imbed themselves in.

The easiest way to think of friable crystals is to envision two types of diamond crystals. Keep in mind there are many other types of crystals, not just these two basic examples. Think of a crystal shaped like an ice cube, and another crystal shaped like a pop sickle stick.

The friable crystal is the pop sickle stick and the ice cube is just a typical diamond crystal that is found in most standard grades of diamond polishes.

Note: These examples are very simplified for explanation purposes, diamond crystals in real life would have similar shapes, but of course be much more irregular.

As you can see there is a significant difference in the crystal shapes and because of the shape differences these diamonds polishes will cut and polish quite differently from each other.

Left: Standard diamond crystal.
Right: Friable diamond crystal.

cubepop sickle

As you can imagine from the crystal shapes as the diamond crystals are used and start to wear there is significant differences between the two different types.

Left: Standard diamond crystal.
Right: Friable diamond crystal.

worn cubepop sickle as it breaks up from wear

What essentially happens to the cube or more blocky diamond crystal of the typical diamond polish is that the crystal wears on the corners and the cutting/polishing action will slow down as the diamond crystal's corners/edges become dull. That is why recharging is needed.

As you can see on the friable crystal, the pop sickle shaped crystal, because of the longer narrow shape the crystal breaks down into smaller crystals. And because the crystal breaks, it leaves new, smaller sharp cutting edges that increase polish speed and make a finer polish.

Because of the way friable diamond polishes are designed to break down into smaller shape crystals during the cutting or polishing process, friable diamond polishes are quite a bit better, especially for polishing on hard laps.

Friable diamond polishes are faster, finer and just generally better than standard diamond polishes, depending on the application. Friable polishes cost a little more, mainly because of the much finer grading process that they are put through.

All diamond polishes are not created equal. The finer the grading, and the more fiable the diamond polish the better it works for polishing. If you try friable diamond polish you may find they work a little different and usually better than what you maybe used to. But it does depend on the laps and the stones you are trying to polish.

Jeff R. Graham

The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as Gram Faceting Designs.

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