Vintage signed blue aquamarine Mexican silver ring

Vintage sterling silver ring with diamond cut pear shaped blue aquamarine stone. Gorgeous artisan signed ring marked with Mexico, eagle assay mark with what appears to be C6?, and artist's initials as shown. I believe the stone is an aquamarine and not a blue topaz, but I'm not a gemologist. Stone is much prettier than photos suggest and measures 3/8 by 5/8 inches. Measures 16mm in diameter (US size 5 and 1/2). This ring is one of several pieces of vintage jewelry we acquired last year from a woman who had collected Native American and Mexican silver from the 1940s through the 1970s. Her pieces included many designed by coveted mid century artisans and designers including Castillo, Margot de Taxco, and Native American artists Lee and Mary Weatherbee.

$79

(3017-vintage sterling silver Mexico signed artisan ring aquamarine)