Fish-eye cut ray path displaying unplanned light leakage
A white frosty ring is a reflection of a bruted girdle (diamond edge) bouncing of the bottom of the diamond (pavillion) due to a shallow cut.
A fish-eye is a reflection just inside the table of girdle (on the opposite side). If the girdle is not polished and is thick the effect looks like a BIG circular inclusion, and can be as bad as an I3 (P3).
Fish-eyes are more apparent if the pavilion is shallow 39.5°, the table is large; the girdle is thick and not polished. Combinations of these factors worsen the effect.
Fish-eyes are more apparent if the pavilion is shallow 39.5°, the table is large; the girdle is thick and not polished. Combinations of these factors worsen the effect.
Fish-eyes occur proportionately between the following pavilion depths and table sizes:
41 degree pavilion and 72.2% table
39 degree pavilion and 58.4% table
In simple terms the diamond is too shallow and the diamond table is too large (spready).
A white frosty ring fills the centre of the diamond affecting the diamond’s transparency.
This white frosty ring is a reflection of the girdle ( usually a bruted girdle not faceted) reflecting off the pavillion facets.
These fish-eyes require no tilt to see them. If the table gets 1% bigger you see a 1% fish-eye.
Fish-eyes are rated with a negative value that treats the effect like an inclusion, because that is what it looks like.
No tilt required is the worst fish eye, and should be accompanied with a warning, “do not buy this diamond under any circumstances as it is a fish-eye.”
A small amount of tilt to see a fish-eye is acceptable to some people because these diamonds have a very good spread and look very big for the money.
A fish-eye is an unattractive appearance that you can see just inside the table of a diamond. It looks slightly crazed,dull similar to a dead fishes eye, affects the transparency and downgrades the clarity grade.
Do NOT buy SOLITAIRE fish eye diamonds. They are not quality.
If you are offered a fish eye realise these diamonds are very cheap on a per carat basis. A fish eye however that is bordering on the edge before it becomes quite apparent is an excellent bluff stone and will have an enormous spready table. I call these ” Show for Dough($$$) Stones “. Often these type of diamonds are seen on women who rather desire the large size diameter because to them it’s the large size that impresses and it is what they want more out of the diamond rather than the higher quality.
As they say in the classics, horses for courses.
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Small fish eye diamonds and / or heavily included white diamonds can be used to give a cracked icey affect in diamond cluster designs in conjunction with good transparent diamonds making an excellent contrast.
This innovative technique is employed by Fawaz Gruosi de Grisogono in his ” Icy Diamond ” range.
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