Gems

Gems are a valuable material that can only be found in veins underground, embedded in Stone blocks, which will only drop the gem when mined.

Each gem colour can be used to create a Phaseblade of the matching colour (but with identical attributes), while Topaz are used to craft the Sandgun and Rubies for the Gold Crown and the Robe. Additionally, each component of the Jungle Armor requires 2 different gems to be crafted; crafting a full set requires various gems of all types.

Gem rarity is not affected by depth; you will find as many gems near the surface as right above the Underworld. Some gems are less common than others; refer to the list below for each gem's rarity, in descending order.

Phaseblades
Gems can be used to craft Phaseblades:

Other Recipes
Some gems can be used in the crafting of individual items:
 * Topaz: Sandgun
 * Ruby: Gold Crown
 * Ruby: Robe

Also, the crafting recipe for the full Jungle Armor includes every kind of gem:
 * Emerald + Sapphire: Jungle Hat
 * Ruby + Diamond: Jungle Shirt
 * Amethyst + Topaz: Jungle Pants