What is the difference(s) between a precious and a semi-precious gemstone?

Precious stones vs. semi-precious stones is not a scientific categorization. Traditionally, the precious stones--which included diamond, ruby, sapphire, emerald, and amethyst--were much harder to obtain than other gemstones, like hematite, quartz, jade, carnelian, turquoise, etc.

Because of their rarity, the precious stones cost a great deal more, so they were out of reach of the common people. Their use was confined to the nobility and the clergy, which increased their mystique.

But "rarity" changes. In the 19th century, huge deposits of amythest were found in South America, and the value dropped significantly. It is no longer considered a precious stone, although some colorations, like the rare Russian Blue, are still extremely valuable. In addition, modern mining techniques make diamonds very common, however their introduction to the market is controlled so that their value and price are kept high.

Semi - precious gemstones : amethyst, topaz, garnet, citrine, peridot, aquamarine ...They are considerably cheaper than the precious ones, and are often used in the manufacture of cheap 9 - carat jewellery or marcasite silver jewellery.

Precious stones are largely determined by a history of ecclesiastical, devotional or ceremonial use and rarity. Only 4 types of gemstones are considered precious : diamond, ruby, sapphire and emerald.

Basically, what separates them is the availability. Tanzanite used to be considered semi-precious, but now with the civil war in Tanzania, and the fact several of the mine have been flooded, it is considered precious.

PRECIOUS

diamond

ruby

emerald

SEMI

Lapis

Jasper

Hematite

and yes AMETHYST (NOT considered precious)

c-ya

Only five types of gemstones were considered precious: diamond, ruby, sapphire, emerald, and amethyst.