Cleavage

it is always harder to find a "mind clean" stone than a eye clean stone.

What exactly is cleavage anyways?

Hi V1023:

Cleavage is a feather or crack that formed along the atomic growth plane. What is important to consider is the size and location of the cleavage, and whether it breaks the outer surface of the stone. The determination of the chances of breaking needs to be assessed for each diamond by an expert or appraiser. Diamonds can cleave if hit on the cleavage plane. Open feathers can sometimes spread.

There are some companies that will "fill" cleavages (fractures) with a glass like substance which causes the fracture to be much less noticeable to the naked eye.

Josh Rioux
Haines, Alaska
*The Colored Gemstone Nut*

Gary

www.diamondexpert.com

Hey Phillip: Here's a little more info on cleavage

Diamonds have perfect cleavage in four different directions like Garry outlines, meaning a diamond will separate neatly along these directions rather than break in a jagged manner. The lines of cleavage result from the diamond crystal having fewer chemical bonds along the plane of its octahedral face than in other directions.

Cleavage (crack or break) is described as a break in a diamond parallel to a cleavage plane. Fracture is a term used to describe the chipping or breaking of a stone along a direction (other than) a cleavage plane. A feather is decribed when the plane of cleavage or fracture in a diamond is viewed in a direction normal to it, the appearance is often reminiscent of a feather, which in the photo is what I believe contributes to this si-2 clarity grade

If it reaches the surface, especially at the girdle, it could pose a durability problem as Garry points out. The strength of diamonds is mainly endangered by fractures, especially the ones that reach the surface of a stone... when such a diamond gets a hard blow, it can potentially split. Hit a diamond in one of the four directions of cleavage and the diamond chips, usually from the girdle and toward the culet.

This, of course, depends a lot on the size and depth of the cleavage-feather-fracture. In other words the basic difference between a feather and a cleavage is that the cleavage runs parallel to the cleavage plane, and a feather is not parallel to the cleavage plane. The primary cause of diamond chipping and breakage is cleavage.

As far as affecting refraction, I am not sure if it would affect the rays of light and how they are dispersed through the crown? Garry, Sergey, Jonathan??

Hope this Helps...

Josh Rioux
Haines, Alaska
*The Colored Gemstone Nut*