Diamond clarity is one of the classic 4Cs of diamond quality. In terms of the appearance of a diamond, clarity is one of the most significant attributes.

A diamond that is heavily flawed and carries a low clarity grade will not have a good sparkle or brilliance. A low clarity diamond will have visible flaws, called inclusions, inside the gem that can even lead to a lack of durability in the hardest natural substance known to man!

To help jewellers and buyers of diamonds and jewellery to make an informed choice, the GIA (Gemological Institute of America) devised a scale for the grading of diamond clarity. The goal was to have a scale that was objectively described running from flawless to obviously flawed.

The GIA scale, which is also widely used by other diamond grading laboratories runs from FL (flawless) to I2, which means obvious inclusions under magnification and possibly to the naked eye.

There is no SI3 grade on the GIA clarity grading scale, or on the scale as used by most other grading labs. The relevant GIA grades are SI1 and SI2 next comes I1. So, where does the SI3 grade come from that many diamond buyers are seeing?

There is just one diamond grading agency that uses the SI3 grade, European Gemological Laboratory (EGL). And, if you want the story fast, the SI3 grade is designed to con buyers out of money by selling low-grade diamonds at a higher price than they deserve. Don't buy SI3 graded diamonds!

What Is SI3 Grade?

In the industry-wide grading scale, SI1 and SI2 diamonds have minor inclusions under magnification. Occasionally these inclusions might be noticeable to the naked eye, but this will depend upon the cut of the diamond and the location of the inclusion.

Many buyers look to the SI grades for diamonds that offer the appearance of clarity in day to day use. This level of clarity is called 'eye clean' comes at a much lower cost than more perfect gems. On the other hand, I graded diamonds will rarely be eye-clean. I grade is, therefore, a big jump downward in quality.

In terms of the wording of the grading report, an SI grade diamond will have noticeable flaws. I grade diamonds will have obvious flaws that affect both brilliance and transparency.

The eye clean nature of most SI diamonds makes them a top-rated buy for many buyers who can save money and potentially buy larger gems within their budget. The only person who will ever know the diamond is an SI diamond and not the higher graded VS grades is a jeweller. In ordinary life, nobody will notice or care about the difference.

It is not hard to recognise an I grade diamond by the visible flaws on close inspection, and the lack of brightness of the diamond in day to day wear.

Where Does SI3 Clarity Grading Come From?

EGL introduced the SI3 grade to help vendors sell inferior gems that most buyers would otherwise reject – diamonds from the I clarity grades. Unsuspecting buyers are getting I grade diamonds at SI grade prices.

Because clarity is such a vital part of the appeal of a diamond, buyers want to get the best diamond clarity they can for their money. The new EGL grade SI3 is equivalent to I1 or I2. Most customers want to buy SI grade diamonds, the EGL grade SI tricks them into buying I grade diamonds.

Most reputable jewellers only sell graded diamonds with the GIA certification so that you can be sure of a consistent quality assessment between retailers and from diamond to diamond. When you see a diamond graded as SI3, it will almost always be sold at a price only slightly lower than SI2 diamonds and higher than I1 or I2 diamonds. The proper valuation should be the same as the I1 gems.

Is There A Problem With SI3 Grading?

Apart from the pricing issue, there are other problems. For example, when you add a piece of jewellery with an SI3 grading to your insurance, some insurers will not recognise a certificate from EGL, especially if the item was expensive. Insurers will ask you, at your expense, to obtain a GIA certificate for the gem. Getting the GIA report will cost money and, of course, the owner will have the disappointment of receiving a grading of I1 or I2. The insurance valuation will almost certainly be significantly lower than the price initially paid for the jewellery.

When you want to sell a piece with an SI3 diamond, the buyer will almost certainly give a valuation based on its real grade – I1 at best, leading to disappointment to the seller.
Another issue faced by buyers of SI3 diamonds is that the diamond often does not have an independent certificate at all. The jeweller will not even bother sending the diamond to EGL for grading and apply the grading themselves to their I1 and I2 diamonds.

Are There Benefits To SI3 Graded Diamonds?

There are two possible benefits to SI3 graded diamonds:

1. An apparently lower price
2. You can tell everyone it is an SI graded diamond

These seeming benefits are not real. What has happened is that the buyer has overpaid for an I1 or I2 diamond. For the latter benefit, given that flaws at this grade are obvious, the only words to say are 'who do you think you're kidding!'

Buying an SI3 diamond knowing the reality of the grade is an act of self-deception.