This is a spectacular and unforgettable sterling and amethyst necklace. It was made by Alfredo Villisana who worked for two of the most renowned silver makers in Mexico - William Spratling and Hector Aguilar. It is marked with an Eagle 3 and his own personal stamp. I cannot begin to tell you how amazing this necklace is. It is impeccably designed and made. The clamshell shaped sterling cup holds a huge polished amethyst. Four curled wires hold it in place and they embellish the design perfectly. The necklace is rigid but you will note three hinges near the back of the piece. It ends in a sturdy box clasp which is easy to remove. The necklace is about 14 1/2" around. It is a little over 1/2" wide at the clasp and narrows down where it holds the pendant. The pendant is just under 2 1/2" top to bottom and 2" across at the widest part. The amethyst is about 1 3/8" x 1" at the widest parts. It is free form just as it was found in nature. You will note that the cup holding the stone is shaped to mimic the shape of the stone. Necklace is in excellent condition with old patina. I have not cleaned it at all. The black spot at the top of the pendant is a reflection of the camera - there is no black spot on the jewelry. This show stopping necklace weighs about 85 grams. I would date it to the early 1960's.