Gemcorns

(Note) Gemcorns do not need to be planted underground just on stone.

Gemcorns are a type of Seed whose saplings grow into Gem Trees. They can be crafted from an acorn and a gem. Gemcorns must be planted in the Underground layer or below on Stone, Moss, or any of their biome variants, and the 3 blocks on each side of the planted one must also be one of these. Chopping down a Gem Tree will yield 10-20 Stone Blocks, 0-5 Gemcorns of the tree’s type, and 0-5 Gems of the tree’s type (To be more precise, each tile of the tree has a 1/10 chance of dropping a gem (if it doesn't drop a gem, it'll always drop a stone block), and every leaf tile additionally has a 1/2 chance to drop another gemcorn.)

Farming
Farming gemtrees requires only an open space in the underground layer or below. Light levels do not affect the growth of Gemcorns at all. Natural Gem Trees can be found in the Underground layer and Cavern layer, although they are rare.

Background Walls
To reduce mob spawning in a Gemtree farm, it is possible to place background walls in almost all of the background, except the two spaces occupied by the placed Gemcorn (this trick is commonly used to make indoor tree farms). Some underground enemies (and critters) will still spawn, but far fewer than with an un-walled farm.

Gemcorns can grow in front of fences like other trees. They can also grow in front of natural dirt or other underground walls (such as mushroom, lava, dirt, stone, and the Underworld's background). Of course, natural walls will allow enemy spawning as usual.



Spacing
The Gemcorns must be planted with three tiles of space from other saplings for both to be able to grow.

Gemcorn saplings need at least 11 blocks of "head room" above them, but 16 blocks is better, and 17 will avoid the topmost leaves clipping into the ceiling. The tree size is determined every time the sapling attempts to grow, and if there are fewer than 16 blocks the attempt will fail. Thus having less than 16 blocks available will effectively slow down growth, and will produce only shorter trees (which will yield fewer gems).

Tips

 * Using different-colored gem torches or Gemspark Blocks beneath each sapling can be a good way to indicate which type of tree is planted where. Alternatively, paint can be used on the other blocks (as in the picture); a gemcorn planted on a painted block will sprout into a painted gem tree (just as it would with other types of trees) that could instead make it difficult to see the type of gem due to the coloring.
 * However, using the Illuminant Paint on the actual blocks where you plant your gemtrees could help to tell the gems apart, since it causes the trees and the colored gems on it be fully visible, regardless of lighting (or lack thereof).
 * Gemcorn trees will grow faster when placed further apart, but times will still vary.
 * Gemcorns can be sold for the value of their respective gem.
 * While diamond and amber sell for the highest price directly, any gem except diamond can be crafted into Stained Glass worth, requiring 5 blocks of glass.
 * While Gemcorns can be planted on mossy stone, the outgrowths of moss can block the sapling's growth. Furthermore, while a single stroke of a pickaxe will normally remove moss from stone, this doesn't work if a Gem Tree has grown on the block.  (Moss can still be removed from beneath a sapling.)