One of the demanding techniques the Los Castillo workshop is credited with, onix negro (black onyx) was introduced by them in the world of Taxco silver-smithing in the early 1950s and it has resulted in some amazing pieces of jewelry. Set within a carefully carved piece of flat-cut black onyx, the silver elements of a design are then ground down to match the stone surface in a seamless, perfect plane. The technique was picked up and experimented with by a few other Taxco maestros and it was also at times simplified to an extent that rendered it unrecognizable yet here we see it at its truest, most demanding form. But then again, one wouldn't expect anything less from the Los Castillo... Measuring 2 1/2" tall (including the cascabeles) by 1 3/4" wide the brooch weighs 33.7 grams. It is fully signed with the workshop's name as well as "HECHO EN MEXICO", "ONIX NEGRO", des. no 43 and what seems to me to be a small part of an Eagle assay stamp inside the circular signature mark (if that is not the case, we will have to reconsider the date for the technique's birth). It dates ca 1950 and is in excellent vintage condition with good weight, great craftsmanship, beautiful patina and no damage or repairs noted.