Some gems, like diamond, are highly coveted but can be unattainable, especially in the sizes and quality people dream of owning. Synthetic gems offer you the best of both worlds. You get the beauty of a beloved, rare gemstone, but at a price you can afford. The term synthetic refers to a man-made material with a natural counterpart. The synthetic crystal replicates the chemical, optical and physical properties of the natural diamond with little or no variation.