There are two categories of gemstones: precious and semiprecious. But did you know that there are only four types of stones widely accepted and characterized as “precious”? It’s true. Of all the gemstones mined, collected, sold, traded and valued in the world there are only four valued enough to be considered precious!

So which lucky four made the cut? Those four stones considered precious are emerald, diamond, ruby and sapphire. These four stones are highly valued worldwide for their hardness and rarity. Diamond wins for hardest mineral and though the gem itself is not entirely rare, the clear white variety most preferred by jewelry lovers today is certainly difficult to come by.

Though not accepted across the table as precious stones, there are a few more stones out there considered by some to be precious. These include both varieties of corundum and precious opal. In general, however, diamond, ruby, emerald and sapphire make up the precious stone category.