According to national standards, gemstones are divided into natural gemstones (natural gemstones, natural jadeite, natural organic gemstones), artificial products (synthetic gemstones, artificial gem, mosaic gemstones, recycled gemstones) and imitation gemstones.
1. Natural jewelry and jade
(1) natural gemstones
Especially mineral single crystals produced in nature. There are many varieties. Gem researchers often use mineralogical classification method to subdivide gems into families, species and subspecies, while gem traders often divide gems into high, medium and low grades according to the law of value, and some divide gems into ordinary and rare ones according to the scarcity degree.
A. division of families, species and subspecies of natural gemstones:
Family-refers to a group of isomorphic gems with similar chemical composition and the same crystal structure. Such as garnet family and pyroxene family.
Species-refers to gems with the same chemical composition and crystal structure and similar appearance.
Subspecies-a further subdivision of species. Refers to the same kind of gem, which has obvious changes in appearance due to different trace components in chemical composition, such as yellow sapphire in sapphire.
B. classify natural gemstones according to their value and scarcity:
① High-grade gems: diamonds, emeralds, rubies, sapphires and emeralds (rocks, cat's eyes);
(2) middle and low-grade gems (ordinary gems);
3 Precious stones: For example, Tafei stone produced in Sri Lanka has beige, lavender, reddish and other colors, with little output and low market awareness.
(2) Natural jade
It refers to the mineral aggregates and a few amorphous bodies (natural glass) produced in nature with beautiful, durable, rare and scientific and technological value, which are collectively called natural jade. Jewelry industry is used to dividing materials into high-grade jade, middle-grade jade and stone carving according to their use history, market value and technological characteristics.
A. High-grade jade: such as jadeite and nephrite, referred to as jade for short.
B middle and low grade jade: agate, chalcedony, azurite and serpentine.
C. stone carving: jade with low hardness can be carved with a steel knife. Mohs hardness is usually less than 4. The main products are seals, inkstones and decorative stones. A few of them are of high value, such as Tian Huangshi and precious bloodstone.
(3) Natural organic gemstones
Refers to the biological solids in nature, which are partially or completely composed of organic substances, and some of them are themselves part of organisms, such as ivory and tortoise shells. Cultured pearls are also classified as natural organic gems because of the imitation of nature and the simulation of products in the breeding process.
2. Artificial products
(1) synthetic gem
The physical properties, chemical composition and atomic structure of all or part of artificial materials are basically the same as those of corresponding natural gems, such as synthetic rubies and synthetic emeralds;
(2) artificial gem
Artificial materials are usually similar to some gems in appearance (similar to imitation gems), but their chemical composition and physical properties are different, and there is no natural counterpart, such as yttrium aluminum garnet and gadolinium gallium garnet.
(3) Assembling gems
Refers to two or more kinds of materials put together by artificial methods, which gives people an overall impression in appearance, and is called a mosaic gem;
(4) Rebuilding gems
It is made of fragments and chips of some natural gems by artificial fusion. Common recycling amber and recycling turquoise.
Imitation gem
Materials, such as glass and plastic, which are completely or completely made by human beings and imitate the effects, colors and appearance of natural gems or artificial gem, but do not have the chemical composition, physical properties and crystal structure of the imitated gems.