The brooch is oval in shape and measures 1" x 3/4". It does not have a gold mark but was tested with nitric acid and a "kee" tester to be 18k solid white gold. The piece weighs 4.9 grams and set in the center is a London blue Natural Topaz. The topaz looks to be cut like the letter M. It has an approx weight of 3.50 cts. The topaz is surrounded by natural brilliant cut diamonds and the oval part of the brooch also has brilliant cut natural diamonds. The 55 diamonds have an approx total weight of 1.10 cts. The range from SI1 TO SI3 and H to I in color.