What is a diamond or gemstone still worth when you sell?

The hard news about gemstones when selling gold

When people want to sell their gold jewellery, they sometimes hope for a bonus thanks to the gemstones in it. A ring with a diamond must be worth more than one without, surely? In theory perhaps. In practice, gemstones are almost always worthless to a gold buyer.

This article explains why the market for gemstones has changed drastically in recent years, what lab-grown diamonds have to do with it, and what this means if you want to sell a piece of jewellery with stones.

The figures: how sharply diamond prices fell

These are not small corrections. This is a structural upheaval of a market that seemed stable for decades. Reduced demand from China, fewer marriages, economic uncertainty: all these factors contributed. But the main cause is the massive rise of lab-grown diamonds.

What are lab-grown diamonds?

Lab-grown diamonds are real diamonds, chemically and physically identical to mined diamonds. The only difference is the origin: they are not formed in the earth over millions of years, but in a laboratory in a few weeks or months.

There are two production methods:

In both cases the result is a diamond that even an experienced jeweller cannot distinguish with the naked eye from a natural stone. Specialised gemmological equipment is needed for that.

Why are lab-grown diamonds so much cheaper?

In the past, lab-grown diamonds were about half as cheap as natural diamonds. Now they are often 60 to 95 percent cheaper. The reason is simple: production costs fall continuously through technological improvement, while supply rises sharply.

Natural diamonds require expensive mining, complex logistics and extensive certification. Lab-grown diamonds need none of that. They are also more ethically attractive to younger buyers: no conflict diamonds, a traceable origin and a lower ecological footprint.

The result: in 2024 more than 45 percent of all engagement rings in the United States featured a lab-grown diamond. In 2019 it was only 12 percent.

Are gemstones a good investment?

Short and clear: no.

Lab-grown diamonds are not an investment. Their value falls continuously as production becomes more efficient. The trade-in value is usually 10 to 40 percent of the purchase price. Whoever buys a lab-grown diamond buys a piece of jewellery, not an investment.

Natural diamonds hold their value slightly better (20 to 60 percent residual value), but that market is under pressure too. Rare, exceptionally large or historically significant diamonds can retain their value or even see it rise, but that applies to a very small segment of the market.

For most consumers: a diamond is a beautiful piece of jewellery, not a piggy bank.

What does a gold buyer do with the gemstones?

When you sell a gold piece with gemstones to a gold buyer, the gold is weighed and paid based on the current gold price. In most cases the gemstones are not compensated, or only symbolically.

The reason: small diamonds and other gemstones are difficult to trade without expensive gemmological certification. The cost of having a stone assessed, certified and resold often exceeds, for small stones, the selling value itself. Certifying small diamonds is therefore not financially worthwhile: the costs of removing the stone, sending it and repolishing it are often higher than the added value the certificate brings.

How do you recognise a lab-grown diamond?

With the naked eye it is impossible. Even for experienced jewellers the difference cannot be seen without equipment. Only specialised instruments from institutes such as the GIA (Gemological Institute of America) or the IGI (International Gemological Institute) can tell them apart.

The most reliable proof is the certificate. A GIA or IGI certificate always clearly states whether the diamond is natural or synthetic. Do you have a certificate with your jewellery? Keep it well.

Frequently asked questions about gemstones and selling