Signed on the back of the setting "China, 925 and a diamond shaped emblem with marks inside that I am not familiar with. It is the same emblem shown in the picture of the metal tag on the chain. 

The chain measures 18 inches long. The pendant is 7/8ths inch long x 5/16ths inch wide x 1/4 inch deep. 

Gorgeous blue faceted topaz set in double prongs. The 3 beautiful oval opals are prong set, also.  Much sparkle from this piece. Gold tone sterling makes this a very rich looking piece. The chain matches in color. The chain can be changed easily as the pass through area for the chain is on the back and will allow for a thicker chain if you so choose.