Opal, or "golden emerald with cat's eye effect". Also known as "cat's eye", "cat's eye", "cat essence" and oriental cat's eye, it is a rare and precious variety in jewelry, also known as Alexander's cat's eye, which has both discoloration and cat's eye phenomenon.

Opal is one of the rarest and most precious emeralds. Only Sri Lanka is produced in the world, and the price is quite expensive. /kloc-It's hard to see domestic shopping malls above 0/0 carat. Opal is named because it is as flexible and bright as a cat's eye and can change with the intensity of light. This optical effect is called "cat's eye effect".

Opal is one of the golden emeralds in mineralogy and belongs to the golden emeralds family. Gold emerald is an alumina containing beryllium, and its chemical molecular formula is BeAl2O4. It belongs to orthorhombic system. Crystal morphology is often short columnar or plate-shaped.

Strictly speaking, "cat's eye" is not the name of a gem, but an optical phenomenon presented on some gems. That is, when a semi-spherical gem is irradiated by strong light, there will be a narrow and bright reflection on the surface, which is called "cat's eye flash" or "cat's eye live light", and then it will be named according to what the gem is. If the gem is in season, it will be called "quartz cat's eye", and if it is golden emerald, it will be called "golden green cat's eye".