What Unheated Means, and What It Costs

Most sapphire and ruby on the market has been heated. The practice is roughly two thousand years old, and it is honest work when it is declared. Heat completes what the ground began. The stone that never needed the furnace is the exception, and markets price exceptions.

The premium for an unheated stone of equal face is real. Thirty to fifty percent for fine sapphire, more for Burmese ruby at the top of the scale. You are paying for rarity, and you are paying for proof. The proof belongs to the laboratory, never to the seller. Gübelin, SSEF, AGL and GIA will each state, in their own careful words, that a stone shows no indication of heating. Those words are the asset.

When is the premium worth paying. For investment, almost always. The certificate line is the part of the stone that has appreciated fastest for thirty years, and supply of certified unheated material shrinks every season. For a piece that will be worn and loved, judge with your eyes. A superb heated Ceylon sapphire beats a mediocre unheated one every day of the week, and at half the money.

My own rule is simpler. I buy the stone first and the word second. Then I send the word to Lucerne and make it prove itself.