It is important to note that this is not a diamond tester. You must be quite certain that you are 'screening' known diamonds. So please do not buy this if you are not already an expert in diamonds, or if you do not already have a diamond tester).

A serious tester for the professional jeweller, it helps screen out Type II diamonds, these are very rare in nature (2%) but, currently, all synthetic (CVD and HPHT) diamonds are of this type. For colour range D to J.
Synthetic diamonds are diamonds, they are real diamonds*, they are grown by man in a laboratory instead of being grown by nature in the ground. Do not confuse this with a ‘simulant’ - a stone that might look like a diamond but is not. Since synthetic diamonds are the same as natural diamonds, they are extremely difficult to detect, and up to now the only testers were expensive. This is the first low-cost synthetic diamond tester and the only one that will test stones mounted in jewellery.

* It is agreed within the diamond and jewellery industries that the description 'diamond' should only refer to natural (dug out the ground) diamonds and not synthetic (grown in a laboratory) diamonds, even though both of these are diamond and not simulants.


Q. What is a type II diamond?
A. Type II diamonds (including Type IIa and Type IIb) have a very slightly different atomic structure to Type I diamonds. Natural diamonds of Type II are rare (about 2%) but it makes no difference to the value, it's just a quirk of nature that makes it possible to detect Type II. All synthetic diamonds (grown by the CVD or HPHT methods) are Type II.

Q. So does that mean if a diamond registers Type II it must be synthetic?
A. No, it means that there's a very high chance that it's synthetic, but there's still about a 2% chance that it is natural.

Q. It says, at the top of this page, "currently, all synthetic (CVD and HPHT) diamonds are of this type" does that imply that this is likely to change?
A. The makers of synthetic diamonds strive to make them so completely identical to natural diamonds that they cannot be distinguished, even on the most expensive machine. Nobody can predict what might happen in the future, but at the moment the two methods used for growing gem-quality diamonds are CVD and HPHT.

Q. If synthetic diamonds are so difficult to detect, and the end product is identical to natural diamonds, why all the fuss?
A. it is standard within the gem / diamond trade to 'disclose' whether a stone is natural or synthetic. Once a synthetic stone (any gemstone, or diamond) cannot be distinguished from its natural counterpart (not by the greatest expert, not by the most expensive machine) then the two become 100% identical. This then poses a problem for the suppliers of the natural stones, e.g. De Beers, who have been concerned, for the last 50 years, that relatively cheap synthetic diamonds could flood the world market. So within the diamond trade, the issue of synthetic diamonds versus natural diamonds is important; for the end-user, each type is as 'real' as the other, and even for the expert, they are extremely difficult to tell apart.

Q. What is CVD and HPHT?
A. They are two methods of growing diamonds that can be used for jewellery.
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.
The 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 in industrial processes.
Q. ...and the point is??
A. It is possible that, one day, someone will invent another method of growing gem quality diamonds which cannot be detected on the Presidium SDS, that is why we say it is suitable for synthetic diamonds that are grown using the CVD or HPHT processes.

Q. I buy dozens (or hundreds) of diamonds at a time, can I pour them all into the machine to see which are synthetic?
A. No, you have to place each one on the sensor, close the lid, press the button and wait a few at a time. However, it is possible to test 7 or 8 per minute.
Q. there anything that will test dozens (or hundreds) of stones at once?
A. Yes, in 2018 De Beers introduced one (model SynthDetect XL), £12000.00 + VAT (this is why I refer to our tester as 'low cost') - we do not this, please contact De Beers for details.

Q. Is there anything else that needs to be mentioned about the limitations of the Presidium SDS?
A. - it works on colourless diamonds, i.e. colour range D to J, not coloured diamonds.
- it works with diamonds of size from 2mm width and up to 6mm high (approx. 0.1 to 10 carat).
- it works with both loose stones and stones mounted in jewellery, mounted stones must have an open back setting


The complete guide to testing diamonds

Distinguishing diamond from Moissanite

Diamond tester trouble shooting

A little about optical gem testers