I have my grandmothers ring and it is marked with 200 ultragem 14k! I see that ultragem is a synthetic diamond from the 70's is this right? Is there a difference between CZ and synthetic? Thank you in advance for your help!!

Synthetic is a blanket term for any diamond that is made in a lab. CZ or Cubic Zirconia is synthetic, but so is (synthetic) Moissanite, which is another diamond replicant. Then there are lab grown diamonds which are made of pure carbon. These are identical to real diamonds in composition. The difference between these and real diamonds are almost impossible to tell using the naked eye.

Hope that helps!