Golden Opportunity. Deep amber and apple-cider gold fire flashes from the heart of this round-cut Zircon. Don't confuse this stone with the name for a manmade diamond substitute, cubic zirconia. The Zircon is, in fact, the oldest gemstone known on earth, while the cubic zirconia is a lab-made diamond substitute. The sophisticated tawny shade is flattered by the classic shape. Gemstone Details