When assessing an 18kt white gold piece, look for '18K,' '750,' or '18ct' stamped on the metal: these are the standard purity marks used by country of manufacture, all confirming the same 750 parts per thousand fine gold content.
Stone Story
Gemstones cut to match a specific geometric setting outline (rectangular, square, or tapered) calibre-cut stones allowed Art Deco jewelers to fill complex geometric forms with perfectly fitted colored stones, producing the graphic, enamel-like color fields that became one of the defining visual characteristics of the period's most accomplished work.
A Storied Heritage
Catholic bishops and cardinals wore september sapphires in their episcopal rings for centuries. Medieval theology put the stone in the foundations of the New Jerusalem. So this isn't just a pretty blue gem: it's one of the most institutionally significant stones in Western history.