The Look of Platinum with a Silver Price Tag" Fine .925 Sterling Silver Jewelry with a Rhodium Finish. Cubic Zirconia is well known as a substitute for diamond, due to its high hardness and brilliance. It has established itself as a gorgeous gem in its own right. CZ is a beautiful synthetic gemstone that is durable and inexpensive and now even comes in any color of the rainbow, making it even more desirable.