Their beauty has captivated us for millennia. Their cost can be extraordinary-some are even considered priceless. Precious gems like diamonds, rubies, emeralds, opal, and jade are the ultimate treasures of the earth, and each one is made from a specific-and often torturous-recipe of chemistry, pressure, and heat.Their beauty has captivated us for millennia. Their cost can be extraordinary-some are even considered priceless. Precious gems like diamonds, rubies, emeralds, opal, and jade are the ultimate treasures of the earth, and each one is made from a specific-and often torturous-recipe of chemistry, pressure, and heat.