Cutting Tigereye Cabochons

Cutting Tigereye Cabochons

Posted by Oak Rocks on 22nd Apr 2023

Cabbing Tigereye to take full advantage of its special beauty takes a little extra care.

In the world of gemstones, there are so many amazing phenomenal stones. Phenomenal stones are those that display an optical effect. The play of rainbow colors in opal or fire agate, stars in rubies or sapphires, the sparkling mica or manmade goldstone, and the flash of color in labradorite or moonstone.

One very popular effect is chatoyance. Chatoyance is a lustrous, cat's eye effect. In chatoyant material, light is reflected in thin needle-like bands all running in the same direction within the stone. Chatoyancy arises either from the fibrous structure of a material, or from fibrous inclusions or cavities within the stone. The name chatoyance comes from the French word chatoyer for "shine like a cat's eye," because it resembles the slit eye of a cat.

Stones that exhibit this effect include Tigereye, Arizona Pietersite, Pietersite, Kyanite, Charoite, and Chrysoberyl, which is usually what people are referring to when they use the name Cat’s Eye.

In chatoyant gemstones, the band may not be visible from all angles. Once found the band of light will move back and forth beneath the surface of the gem as it is turned under a light. The band will also move if the light is moved, or if you move your head to view the stone from a different angle.

Cutting these stones into cabochons can be challenging at first. If the stone is oriented and cut correctly, the band of light should be seen mostly in the center of the stone when you are looking at the stone straight on. The cutter must examine the rough and orient the stone so that the thin bands will be parallel to the bottom of the stone within the finished cabochon, and the parallel inclusions will be parallel to the long axis of the cabochon. It may take a little longer to cut this time of stone, but if done correctly at its well worth it!

Tigereye, a stone in which silica has replaced crocidolite fibers, is by far the most prolific chatoyant stone on the market. Tigereye is vitreous (hard, unbendable and glass-like). The name Tigereye (aka Tiger-eye and Tiger’s Eye) came from its chatoyant cat's eye effect.

When cutting or cabbing Tigereye, to produce a good chatoyant effect, the fibers should be as fine and straight as possible. It is very important to cut or buy slabs of Tigereye that are orientated correctly. The slabs should be sawed so that the surfaces are parallel to the plane of fibers. If a slab is cut correctly, you should be able to see the flash of light in the rough material.

To check a slab to see if it is cut correctly, hold the slab parallel to the floor with the fibers running towards you. For this purpose, you are looking only at the fibers, most Tigereye rough will have areas with no fibers or flash. Now look across the surface at an angle of about 60 degrees. The half of the surface closest to you should be dark or light, and the half farthest from you should be the opposite. Mark a light pencil mark at the dividing line between the light and dark. Now rotate the slab 180 degrees and do the same thing. (If the half nearest to you was light the first time, it should still be light after rotating it.) If the stone was slabbed correctly the 2 pencil marks should coincide. Now turn the stone over. If the half towards you was light, when you flip the stone over it should be dark. The surface with on which the light side was closest to you should become your base. If you are cutting an oval orient the dividing line between light and dark right down the center of your oval longwise. Use your stencil to mark out the shape of your cabochon on this side and then cut your cabochon! A medium to low dome cabochon will have the broadest flash. If you have cut just the fibrous area the whole stone should have flash, but it is okay to include some dead zones for an interesting contrast.

You can buy great Tigereye slabs here on Oakrocks! Happy hunting!