The common approach to the question of how UV fluorescence affects diamond pricing is that medium or greater tends to create a somewhat discounted asking price from the more common non-fluorescent and less than medium fluorescent diamonds. As a generalization, this is an acceptable statement, but does not begin to tell the full story.
Right away, we need to separate blue UV fluorescent and some yellow fluorescent from the far more unusual fluorescent colors of white, peach, orange, greenish and red.
Blue fluorescence may cause diamonds with some tint of yellow color to appear more colorless. This is a potentially positive effect on asking price. So long as a diamond does not take on a cloudy or oily appearance due to UV fluorescence, it has little if any effect on what a consumer will choose, but dealers are far more inclined to haggle over the details, even when the details in question are not of much importance to an end user. The GIA allows some amount of UV light into their grading of diamond body color which does change the grading that GIA does from what might happen if no UV light was put into the mix. In the colorless, D-F range, blue fluorescence can’t produce any desired effect. If the fluorescence is not strong enough to be eye-visible in normal wear, then the effect on value is negligible, but if cloudiness or oiliness is visible in normal lighting, then there will be a reason for discounting the asking price.
Yellow UV fluorescence is usually associated with a negative effect on asking price, but it can help the color of a light to strong fancy yellow color diamond to be even more yellow and visible. This is rare, but it is a possibility we should not fail to mention. Truthfully, UV fluorescence of any color which matches, or coordinates in a beauty creating manner, the body color of a diamond may serve to enhance the visual color appearance of the diamond. When this rare but beneficial event occurs, the asking price might be increased. Most UV fluorescence just gives dealers an opportunity to argue over a detail of the value of a particular diamond. It is the free market at work, but it may mean very little to most consumers either in their cost or the appearance of the stone. One thing for sure, UV fluorescence is something that can make the choice of a diamond just a bit more difficult.
In the second hand market diamond dealers will try to offer less for any diamond with any discernible problem or potential issue. UV fluorescence easily fits into this arena since it can be readily shown to the seller and you don’t need to trust the buyer that it is present. That’s how haggling over the buying price is done all over the world, but it is far less common in the USA. Quibbling over the details is how most of the world operates. Fluorescence is just one of many minor and more major small details which diamond dealers suffer over. Other issues are black inclusions, open inclusions, blemishes on the surface, ships, nicks, naturals, symmetry, polish, culet size, girdle thickness, old lab reports, HTHP, laser drilling and several more. The consumer just can’t begin to get into these tiny details in a fully informed way. Sufficient to say is that UV fluorescence of medium or more usually creates an opportunity for the buyer to make a somewhat reduced offer. You may have gotten the right price already, but how can you tell if you don’t ask?
This is the reality of the stigma surrounding diamond’s UV fluorescence. Sometimes any reduction in cost when the diamond enters the market is passed along right to the eventual end user. Many times, this is not the case and the potential discount is taken in by the dealers and retailer as added profit. May consumers find a medium to highly fluorescent diamond very attractive. Dealers may like them a lot, as well, but since they are the kind of folks trained to haggle, that’s what they do. Even when it is not meaningful, haggling is part of the life blood of the diamond trade.
Rapaport and other price guide publishers report minor ranges of premiums and discounts in value for differing degrees and colors of UV fluorescence depending on the color and clarity of particular diamonds. The range is from a few percentage points plus to a few percentage points minus. The reality is that a very few diamonds might gain a bit in value for fluorescence when it improves the way they look, but many have no change or a reduced asking price because of such an effect. We hear of dealers who will not even buy a UV fluorescent diamond simply because it creates a problem in re-selling. We see other dealers who buy diamonds of all types and appear to have little problem with most UV fluorescent diamonds. If you choose to buy a diamond with medium to strong UV fluorescence and ever wish to sell it back into the trade, you should be prepared to have a more difficult time in finding a buyer than if the stone had little to no fluorescence. That’s why it is important to know this before you buy, not years from now. You buy what you like, but you should understand the facts when you choose. My wife has a good sized diamond which does not fluoresce but the 3/4ct side diamonds are strongly blue UV fluorescent. Both of us like the effect sunlight has on them as they turn bluish in bright daylight.
The discount on initial bids for diamonds with strong UV fluorescence can be more than 25% less than for a diamond with no fluorescence. Rapaport does not publish this high a discount in his monthly news magazine. What we get are very nominal indicators of discounts from 0% to about 8% for the most part. I would speculate Rapaport chooses to make these discounts as “minimum discount offer prices” just as the main “highest asking prices” on his Rap Sheet do not reflect the best prices, but the highest range. It is all very logical, but might escape the consumer who is not so well aware of how the Rap pricing guide is a coded sheet for which outsiders have no key to full understand. Even highly experienced estate dealers do not have the complete key to the pricing in the diamond market. The key is earned knowledge by working daily in the diamond business. There is no other way to be kept current. The best we can do is to generalize and to keep the consumer aware of the issues. The diamond business may seem somewhat simple on the surface, but underneath the glitter there is a complex free market trading and moving 24/7 all over the world.
Consumers may find a UV fluorescent diamond is the one they most prefer. Often there is no visual basis for any discount and on occasion the right color of fluorescence and a particularly well matching body color may create a meaningful premium value. The free market will always act to create the minimum of buying costs when a consumer wishes to sell back to the trade. In the several steps a diamond takes to get back to the next consumer that discount may be mitigated. The final asking price may be adjusted for the particular issues of the diamond, or may be priced based simply on shape, cut quality, weight, color and clarity. We can’t know until each stone comes back to the end user exactly how it will be priced The consumer is best left to understand that UV fluorescence and pricing differences make sense, but don’t always occur in apparent and simplistic ways in the final retail asking price. In the end, you must select what pleases you the best. Knowing the facts can give you a lot more comfort in your decision process.
David Atlas, GG, Certified Senior Member, NAJA