Abstract: The present disclosure relates to methods for improving the quality of diamonds by eliminating internal defects, such as cracks and vacant volumes, without the use of filler materials such as glass, thereby improving the diamond's optical performance or appearance. More particularly, the disclosure relates to a method of curing defects in a genuine or synthetic diamond or other gemstone by using Atomic Layer Deposition (“ALD”) processes to form atomic layers within vacant volumes or cracks in the diamond or gemstone. Alternatively, ALD may be used to form crystalline layers of a new diamond or other gemstone.