Crystals can be made artificially but a lot of energy is used to melt the ingredients together, and this can make them expensive. This problem can be overcome by using appropriate solvents. Called the flux method, crystals are grown in a crucible that contains solvents that allow the crystal to form with less energy because dissolution will happen more easily. Imagine having table salt and wanting to form crystals of a desirable structure. The salt can be heated to its melting point which would take a lot of energy, or, it can be dissolved in a solvent such as water, and the water can be evaporated at a much lower temperature than trying to heat the salt on its own. Finding the right conditions is key for having good crystal recipes.
Click here for original story, Rubies on sapphire: Recipe for making crystals in flux
Source: Phys.org