Can you tell the difference between lab-grown and natural diamonds? Yes, and no.

2024 has been the year of the lab-grown diamond in South Africa and, with sales rocketing, customers are looking for reassurance that in the jewellery industry, we can tell the difference between lab-grown and natural diamonds. Suppose a customer wants to purchase a natural diamond (or a piece of natural diamond jewellery). In a case like this, they want to be sure the diamond or piece of diamond jewellery they’re paying for is 100% natural diamonds. How can they be confident in their purchase? Is there a way to tell the difference between the two? The answer is both yes, and no, depending on the equipment being used.

Is there a difference to the naked eye between lab-grown and natural diamonds?

The short answer to this is “No”. To the naked eye, you will see no visible difference between lab-grown and natural diamonds. When cut and polished properly, lab-grown diamonds will show the same fire, brilliance and sparkle as a natural diamond.

Can a jeweller tell the difference with the naked eye?

The answer is still no. At first glance, with no equipment, neither a trained jeweller nor gemologist will be able to tell the difference between a lab-grown diamond and a natural diamond.

This recent diamond engagement ring we made for a client in South Africa, was made entirely of lab-grown diamonds and set in platinum.

What about using a jeweller’s loupe or microscope?

For the most part, the answer here is still no, but there are some exceptions. Examining a diamond with a loupe or microscope will allow the jeweller to see if there is a laser-inscription on the girdle of the diamond. Many significantly sized lab-grown diamonds have an inscription in the girdle with the lab-grown certificate number inscribed. Natural GIA diamonds are laser-engraved with their certificate number, but there have been instances in the industry where scammers have engraved a legitimate GIA number on a lab-grown diamond.

This lab-grown diamond is easily identifiable with a jeweller’s loupe thanks to it’s engraved certificate number preceded by the letters “LG”, for “Lab-grown”.

The second thing that could help identify a lab-grown diamond from a natural diamond is the style of inclusions in the diamond. Extensive studies have been done on the type of inclusions that occur in lab-grown diamonds vs natural diamonds. Whilst there is some overlap, there are some particular inclusions that are distinct features of a lab-grown diamond. Identifying these in an unknown diamond would mean it has a greater probability of it being man-made. Both the GIA and IGI have issued extensive reports on synthetic diamond inclusions.

A tiny metallic needle-like inclusion is visible in this lab-grown diamond, similar to those described by the IGI as being a “fingerprint” for an HPHT grown synthetic diamond.

How can you tell the difference between a lab-grown diamond and a natural diamond, then?

The answer is that you need to use some fairly specialist (and expensive) technology. These detection devices are becoming more common in the marketplace and more affordable, but we are still not at the stage where every jeweller (or even every diamond dealer) has one or has access to one.

DiamondSure^TM, developed by De Beers, was the first synthetic diamond tester available on the market, back in 1992. This was followed by DiamondView^TM and since then, De Beers has developed 11 diamond screening and verification devices.  Other detection devices currently available include the GIA’s “iD100”, Yehuda’s “Sherlock Holmes” and SmartPro’s “Aura”. Prices range from $6,000 to $35,000 depending on the brand and the model.

Detection machines like these can be used to scan both loose diamonds and diamond jewellery to identify any lab-grown diamonds in a parcel of stones, or in a piece of jewellery. For instance, if you have a tennis bracelet, a detection device can scan every diamond in the bracelet, identifying which diamonds are lab-grown (if any) and which are natural. Of course, if you’re buying an item of lab-grown diamond jewellery, and a natural diamond is accidentally included in the piece, you won’t complain. If however, you’re buying a natural piece of jewellery and it contains undisclosed lab-grown diamonds, this is fraud.

Results of a SmartPro Aura analysis of two cushion cut diamonds, one natural and one lab-grown. The lab-grown diamond (left) was clearly and correctly identified as a synthetic diamond.

Many of the companies behind the detection machine technology won’t disclose what they are measuring or how they are measuring it, and that’s understandable, given that it’s their proprietary technology. De Beers’ DiamondSure^TM machine measures the presence (or absence) of the 415nm optical absorption line which is found in the vast majority of natural diamonds, but not in lab-grown diamonds. By contrast, the DiamondView^TM machine produces a fluorescence image of the surface of a polished diamond, showing the growth structure of the stone. Because natural and synthetic diamonds grow differently, it’s possible to identify one from the other based on the fluorescence image displayed by the machine.

Without high-tech detection machines, however, you stand virtually no chance of identifying a lab-grown diamond from a natural diamond.

We tested a lab-grown diamond ring and natural diamond ring we manufactured, using SmartPro’s Aura machine. The top ring is made entirely of natural diamonds and these appear as blue on the machine’s result. The bottom ring is made entirely of lab-grown diamonds and as such is marked in red by the machine when results are displayed.

What about fancy-coloured lab-grown diamonds?

Like their white counterparts, coloured lab-grown diamonds can be identified using the same detection devices. Natural fancy-colour diamonds are much more expensive than white diamonds due to their rarity and blue and pink natural colour diamonds sell for millions of dollars per carat. Lab-grown fancy-coloured diamonds are much more affordable than natural ones, and as such, more people are purchasing pink, blue, green and orange lab-grown diamonds. If you see these colours in rings or jewellery at retail jewellery stores, particularly in bigger sizes, you may be looking at lab-grown diamonds.

We hope that after reading this you feel more confident that we can tell the difference between natural and lab-grown diamonds. As always, education is key and at Katannuta Diamonds we will continue to prioritise consumer education, first and foremost. You can rest assured that if you’re purchasing a natural diamond item of jewellery from us it has passed the necessary tests. If you’re purchasing an item of jewellery with lab-grown diamonds, we’ll also have tested to make sure that you’re getting lab-grown diamonds and not much cheaper diamond simulants like moissanite or cubic zirconia. Feel free to contact us to commission a piece of jewellery or to ask any questions you need to – we’re here to help.