There are many ways to classify precious and semi-precious stones; one of them is to do it by its origin:

• Natural or original gems
• Synthetic gems those that are made in a laboratory, the product of man's intervention
• Composed by the union of others
• Gems reconstituted  by heat and pressure, for example, tortoiseshell
• Imitation Gems
• Glasses
• Natural pearls, those that are generated by mollusks such as oysters

Color sorting

One of the biggest attractions that a blue topaz as its color, the visual effect they cause is inevitable, and many of these people identify themselves in such a way that they adopt certain stones as talismans only because of their color.

Traditionally, there are some very well-known stones exclusively for their color, such as sapphire (blue), emerald (green), garnet stone (red), among others. Still, in another category of colors, we can find sapphire or garnet itself since be a source stone black mineral, its color can vary but retain the rest of the characteristics of the base stone.

 Red: They are not as common as we think, despite being a primary color, the stones that we can place in this category is ruby, whose name.

In Latin, ruber means red, garnet, and spinel, to name three of the most common. But it is important to note that there are other shades such as a red-orange. It may well be located in this classification or in the one we indicate as orange. corundum red color comes mainly from the iron content in the stone.

Blue: When we think of blue gemstones, a quite high percentage of people will quote us the sapphire, since it is the best known blue stone, but there are more than 35 gems within this blue color range, including black onyx, the same star sapphire, among other.

Greens:  the most traditional and most famous chrysoprase of all is the emerald, whose name comes from the Persian language and means greenstone. But believe it, or not there are more than 50 types of gems within the green color range, including turquoise stone and a type of green sapphire.

Yellow and/or gold: Within this category, we can find a type of yellow sapphire, but the most common is citrine. We also find topaz, agate and amber, and a little more than 15 lesser-known gems.

Violet and/or Purple:  Amethyst is the representation of the violet color in the list of precious stones, accompanied by about 12 more types of them, including a variant of diamond and sapphire in this hue.

Orange: This color is less frequent in gemstones; in fact, its list is somewhat shorter than the rest; however, some such as thickened garnet are still counted.

White: Diamond is king in this category, as are quartz and zirconia, considered colorless gems or aquamarine color gems.

Gray/Silver: Undoubtedly, this color range is the least frequent in a precious stone. However, there are two or three that are well known as aquamarine stone, such as pearl, mother-of-pearl, and moonstone.

Article Source : http://buyloosegemstones.over-blog.com/2020/03/classification-of-precious-and-semi-precious-gemstones.html