Gemcorns



Gemcorns are a type of Seed whose saplings grow into Gem Trees. They can be crafted from an Acorn and any Gem. Natural Gem Trees can be found in the Underground layer and Cavern layer, although they are rare. Chopping down a Gem Tree will yield 7-48 Stone Blocks, 0-11 Gemcorns of the tree’s type, and 0-24 Gems of the tree’s type (each tile of the tree has a 1/10 chance of dropping a gem, otherwise dropping 1-2 stone blocks, and every non-barren leaf/branch tile additionally has a 1/2 chance to drop another Gemcorn.)

Farming
The minimum requirements for a Gem Tree to grow is for it to be planted on one of two immediately adjacent Stone, Moss, or any of their biome variants at Level Underground or lower, displayed by your Depth Meter. Light levels do not affect the growth of Gemcorns at all, therefore you can place light sources nearby to help you see better, although placed torches will prevent tree growth, so do not place any torches within the growing area of the tree (e.g. placing torches below the line of the saplings is fine).

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 between saplings for both to be able to grow.

Gemcorn saplings need at least 11 blocks of "head room" above them, but 16 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 might fail. Thus, having fewer 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.)
 * The required empty 3 adjacent stone blocks to where the sapling will be planted can be hammered to eliminate waste via accidentally planting gemcorns too close together as they can't be planted on hammered blocks.