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CONTENTS

SYNTHETIC-DIAMOND TESTERS DISTINGUISH NATURAL DIAMONDS FROM SYNTHETIC DIAMONDS
MORE ABOUT SYNTHETIC DIAMONDS
QUICK-CHECK FOR NATURALS v. SYNTHETIC  
NAMES: NATURAL, SYNTHETIC, SIMULANT, REAL, FAKE
BUYING GUIDE: SYNTHETIC-DIAMOND TESTERS
TECHNICAL STUFF

This is a specialist article about synthetic -diamond testers. If you are are new to the subject you will find our guide to buying diamond testers and guide to buying electronic gem testers more useful to start with, or you might also be interested in specifically in testing for Moissanite.

We are unique in giving a very detailed appraisal of every product, telling you it’s features and its limitations. Every tester has its limitations, no matter what the make, no matter who you buy it from. 

SYNTHETIC-DIAMOND TESTERS DISTINGUISH NATURAL DIAMONDS FROM SYNTHETIC DIAMONDS

"Natural" means dug from the ground (mined). 

"Synthetic" is identical but grown in a laboratory (lab grown, lab created, manmade). You cannot use a standard (thermal conductivity) diamond tester - that will only tell you if the stone is diamond or not diamond, and both synthetic and natural diamonds are diamonds.   

Natural and synthetic are precise scientific terms. It's OK to refer to natural diamonds as mined. It's OK to refer to synthetic diamonds as lab created, lab grown or manmade.

"Simulant" means a stone simulates another, i.e. you think the stone looks like diamond, but it is not, it is something else.  Beware of other terms, they are usually found in misleading adverts: real, genuine, precious, semi-precious, authentic, simulated. Scroll down to read about the many names people use. 

One simple question

If just want to know if a stone is definitely not diamond (be it natural or synthetic) - then forget about synthetic diamonds, keep it simple, ignore the remainder of this article and go for a simple (£24.50 to £350.00) diamond tester, see article, see the products.  

Synthetic-diamond testers

Note, all the prices include VAT. There is no postage charge for UK orders.

The cheaper models The Ari (by Presidium) £879.00 is for testing stones that you know, for certain, are either diamond or Moissanite, it will indicate synthetic diamond, natural diamond or Moissanite. You must be certain that you are testing a diamond (or Moissanite) because other stones are liable to give false readings. The Arete (by Gemtrue) £730.00 has the same testing functions as the Ari - but we include a standard diamond tester so that you know which are diamond (or Moissanite).  

The latest synthetic-diamond testers distinguish synthetic diamonds, natural diamonds, Moissanite and 'anything else' all-in-one. The latest is the Gemtrue Apex, £995.00; we can get the Presidium Oti £1,399.00 to special order.  

The above is a very short summary, scroll down to our BUYING GUIDE to see how these various models compare. 

All synthetic-diamond testers have limitations on the size, cut, colour and clarity of diamonds that can be tested. They must be:

• brilliant-cut (they testers can give false readings on shallow-cut, including all simple / rose-cut, and fancy cuts. 
• size from 0.02 carat (Oti and Arete) or from 0.2 carat (Apex)
• colour D to J. 
• clarity Fl to Sl1

For the non-expert: you can research the above on the internet, but 'colour' and 'clarity' requires fine judgment and a a lot practise. If this sounds too complicated, see our standard diamond testers (£24.50 to £350.00) and/or our guide to Buying Diamond Testers).  For the professional jeweller: if you work for a group of stores, the company should have a procedure, e.g. you test the stone on a simple tester to see if it might be diamond, then either test it on a synthetic-diamond tester or refer it to your diamond expert.  

MORE ABOUT SYNTHETIC DIAMONDS

Natural diamonds originate as crystals that grow, naturally, deep in the earth, are brought to the surface by volcanic activity, and are mined. They take 2 to 3 billion years to grow. We tend to just call these diamonds without feeling the need to say that they were mined.  

Synthetic diamonds are grown by man in a laboratory (using the same formula nature uses), they take a few weeks to grow. "Synthetic" is the scientific term. Colloquially, these are advertised as lab-grown or lab-created  or manmade diamonds.

Natural diamonds and synthetic diamonds are the same:

• They are the same chemically (carbon)
• They are the same physically (same crystal structure, hardness, density)
• They are the same optically (refractive index, reflectivity, dispersion)
• They can appear the same visually (when examined with a loupe). 

However, most synthetic diamonds react differently if you shine an ultra violet laser through them and measure the response (UV absorption), so you can tell the difference (mostly) but it's difficult to do, which is why these testers are so expensive. 

QUICK-CHECK FOR NATURALS v. SYNTHETIC  

Synthetic diamonds of any significant size (over 1/2 carat) are usually laser-engraved around the edge (girdle) with a serial number. The engraving is a fraction of a millimetre tall, to see it you will need a special extra-powerful magnifier or, better, simple microscope. 

Diamond experts can sometimes tell the difference by examining the stone under a good 10X loupe or, ideally, a good quality microscope to check for inclusions: black specs or tiny crystals (probably natural), fine striations or the 'seed diamond' (probably synthetic).  

NAMES: NATURAL, SYNTHETIC, SIMULANT, REAL, FAKE

Natural. Dug up out of the ground (mined)

Synthetic. Grown in a laboratory (lab grown, lab created, manmade).

Simulant. It might look like a diamond but is not.
e.g. Cubic Zirconia / Cz (synthetic because it doesn't exist in nature)
e.g. Moissanite (synthetic, because gem-quality Moissanite doesn't exist in nature)
e.g. white sapphire (which can be natural or synthetic).  

CVD and HPHT. Two methods of growing synthetic diamonds (more about this below).

Real. Diamond is diamond. If it's diamond it's 'real' diamond. If it's not diamond it's something else. An analogy would be water.*  You would not say, "Is it real water?", you would just say, "Is it water?". 

* to make this analogy simple we'll assume the water is good enough to drink and the diamond good enough for jewellery ("gem-quality").  

Fake, Genuine. This depends on the circumstances:

• You have a ring set with a spinel, you show it to your friends, they ask if it’s diamond and you say no, it’s spinel. It’s not a ‘diamond simulant’, it’s not a ‘fake’, it’s just spinel, that’s what it is, it's a real spinel.
• You are testing stones you think might be diamond, you are only looking for diamonds, you are not interested in anything else, ‘simulant’ means you thought it looked like (simulated) diamond but it is not diamond, it is something else.
• You buy a ring on eBay, the stone was described as diamond, you paid for diamond, it turns out it isn't diamond, it's a fake, it is not genuine.

Precious, authentic. Meaningless terms. How 'precious'?  'Authentic' according to who?

DIAMONDS DESCRIBED AS "DIAMOND" WHEN YOU BUY IN A SHOP

It is agreed within the jewellery industry that jewellers should only use the description 'diamond' for natural (mined) diamonds and not for synthetic (lab grown / lab created, manmade) diamonds. This is a political description not a scientific description. Scientifically they are the same (see above) but politically the description "diamond" should only refer to natural diamonds.  

BUYING GUIDE: SYNTHETIC-DIAMOND TESTERS

Note, all the prices include VAT. There is no postage charge for UK orders.

THE CHEAPER MODELS The Ari (by Presidium) £879.00 is for testing stones that you know, for certain, are either diamond or Moissanite, it will indicate synthetic diamond, natural diamond or Moissanite. You must be certain that you are testing a diamond (or Moissanite) because other stones are liable to give false readings. The Arete (by Gemtrue) £730.00 has the same testing functions as the Ari - but we include a standard diamond tester so that you know which are diamond (or Moissanite). 

This is how the two compare:

Performance: they are just about identical, there really isn't anything to choose between them as far as 'functionality' is concerned. Both will test mounted stones and loose stones. 
Reliability / Returns / Complaints: customers complain that they get incorrect readings when testing non-diamond. I say yet again, these (cheaper) models are for testing stones that you know are diamond (or Moissasnite), to see if they are natural or synthetic. It is also important to remember that there are strict conditions of size, colour and cut, especially the cut because shallow-cut stones give incorrect readings.   
Instructions: the ARETE has a large screen. Instead of displaying a summary of the instructions in words, it plays videos;  the ARI does display 'prompts' on the screen but no instructions, and there is no instruction manual, you have to download it from the Presidium website. So the ARETE is better.
Ease of use: the ARETE is simpler. With the ARI you must very carefully insert the test-tip each time you use it, then diligently remove it when you've finished, which is fiddly. The test-tip is made of glass and is easily broken. With the ARETE the test-tip is fixed to the tester, more robust. So the ARETE is better. 
Size and weight: the ARI is smaller and weighs 60g, the ARETE is larger and weighs 76g. So the Ari is better.
Reputation: Presidium and GemTrue each insist that their products are better than their rival!  Both are leaders in the field of diamond and gem testing. 
Recommendation: the ARI is the best as regards size for carrying in a pocket and is a good choice is you already have a standard diamond tester; the ARETE is simpler to use and costs less and includes a standard diamond tester.

THE LATEST (ALL-IN-1) MODELS distinguish synthetic diamonds, natural diamonds, Moissanite and 'anything else' all-in-one. The latest is the Gemtrue Apex, £995.00; the Presidium OTi  £1399.00 is available to special order. 

This is how the two compare.

Presidium OTi £1399.00 PROS, tests small stones, can cope with some 'fancy' cuts. CONS, alkaline batteries only last for a handful of tests (lithium are better but still don't last long), awkward shape to hold, take care to refer to the instructions, available to special order only, allow 2 to 3 weeks for delivery.  Gemtrue Apex £995.00. PROS, nicely designed, beautifully simple to use,  very clear readings on synthetic diamonds, natural diamonds and Moissanite, tests for ruby/sapphire too. CONS, doesn't test tiny stones or fancy cuts, confusing names ( when it displays "simulant" it means ruby or sapphire, when it displays "Cz" it means other non-diamond). 

FOR LOOSE STONES ONLY

The following (cheaper) models test loose stones only, and you must test one stone at a time (you can't "screen" dozens or hundreds at a time). Our customers are mostly jewellers who want to test individual stones, and the stones will be in jewellery, not loose. For this reason, the following two models are available to special order only: 

Presidium SDS, £779.99, special order only, not on website, delivery 3 weeks. We can send you an invoice then order one for you as soon as you pay.

This is the larger of the two models, there is room to test stones mounted in single-stone rings providing the ring isn't too large and has an open setting and can make perfect contact with the sensor.  

GEMTRUE VERITAS, £590.00, special order only, delivery 2 to 4 months (please contact us for a more precise delivery time), we can send you an invoice and add one to our next regular order as soon as you have paid.

There are testers that screen stones in bulk, they cost £5000.00 to £10,000.00, we do not sell them. 

TECHNICAL STUFF

There are two types of diamond, depending on their atomic structure. This is just a feature of chemistry, it does not affect the appearance of the value. Instead of simply displaying

TYPE I diamonds happen to be natural (all of them).

TYPE II diamonds account for a tiny proportion (about 2%) of natural diamonds but all synthetic diamonds are TYPE II.  This includes both methods of manufacturing diamonds that are used in jewellery, CVD and HPHT. 

So when the tester reads Natural Diamond, it's Type I, but you don't need to know that it's TYPE I because all TYPE I diamonds are natural. When the tester reads Type II, you do need to know, it means there's a 98% chance that it's synthetic and a 2% chance that it's natural.

CVD (chemical vapour disposition) is a type of plating, a mixture of gases is microwaved (or treated with lasers or an electron beam) which causes diamond to crystalise around a 'base' (substrate). The main use of this method is in the electronics and optics industries to 'plate' components with diamond.

HPHT (high pressure high temperature) method involves taking a 'seed' of diamond, and subjecting it to very high pressures and temperatures in a mixture of molten metals (just as they are formed deep in the Earth), a diamond grows around the seed.

There are other methods of synthesizing diamonds but the resulting 'stones' are too small to be used in jewellery, they are used for industrial processes. Our testers are for testing gem-quality diamonds only. 

See also - all electronic testers.
Read all about how to choose a diamond tester (diamond v. non-diamond + Moissanite). 
Read all about how to choose a gem tester.