Diamonds whose clarity is graded SI are popular among buyers as these stones are a lot more affordable than higher clarity diamonds. Let’s see what SI clarity means, how it compares with other clarity grades, and when buying SI-clarity diamonds is a good idea.
SI Clarity and Other Grades
SI diamond clarity is the fifth highest grade in the six-grade scale used by the G.I.A. (Gemological Institute of America).
There is only one lower grade than SI and that is I (standing for “Included”).
The clarity grades preceding SI are (from higher to lower): FL (Flawless), IF (Internally Flawless), VVS (Very, Very Slightly Included) and VS (Very Slightly Included).
What Is SI Clarity?
SI stands for “Slightly Included.”
Diamonds in this clarity range have inclusions that are easy to see under magnification.
Some of these flaws may be visible with the naked eye, but you will still have a hard time seeing them.
This clarity range is further divided into two sub-grades: SI1 and SI2, with SI1 being the higher quality grade.
When looking at an SI-clarity diamond, it is important to also find out the sub-grade of the stone.
Difference Between SI1 and SI2 Clarity
SI1-clarity diamonds have slight inclusions that can be easily seen under magnification. However, these flaws cannot be seen with the naked eye.
SI2-clarity stones, on the other hand, have bigger inclusions, some of which may be visible to the naked eye, although barely.
When looking at an SI2 stone from the top, you usually won’t be able to see flaws; if there are any, they should be barely visible at best.
The flaws that are visible in SI2 stones will be on the side of the diamond. Again, remember that you will still have to look closely to make them out.
So, the biggest difference between SI1 and SI2 is that in SI2-clarity stones, you may be able to see some inclusions, but their visibility depends on the position from which you look at the stone.
Is There SI3 Clarity?
Some vendors use the grade SI3 to refer to diamonds that are not good enough to be graded SI2 but are still better than the stones in the I-clarity range.
Although there are some grading labs that use the SI3 designation, you should remember that this grade does not exist on the G.I.A. scale. Diamonds represented as SI3 are not graded by the G.I.A., which would most likely grade them as I1-clarity stones.
Although there are diamonds for which it can be argued that they fall between SI2 and I1, many sellers use the SI3 grade simply to make I1 diamonds sound better.
So, how do you know that you are dealing with an I1 diamond and not an SI2 stone?
Take a look at the diamond from the top. If you can clearly see inclusions, then the stone belongs in the I1 category; SI2 diamonds should have visible inclusions that can be seen only from the side (with the naked eye); if there are ones visible from the top, they should be barely noticeable.
How to Buy SI-Clarity Diamonds
When you shop for diamonds and you are told that the stone you are looking at is SI clarity, always ask whether it is SI1 or SI2. If the seller doesn’t tell you the exact grade, you should not buy the stone.
Don’t forget to ask for a certificate before you make a purchase so you can verify that the diamond is really graded as it is represented, preferably by a reputable grading lab.
We already saw that the difference between SI1 and SI2 is in the visibility of the flaws. As you might guess, these two grades also differ in price. An SI1 stone can be hundreds of dollars more expensive than an SI2 diamond.
If you want to save money by buying SI2 instead of SI1 clarity, do look at many different SI2 stones and view them from all sides. Some diamonds in this category have inclusions that are more visible, while others have flaws that can barely be seen, and you can get a stone that looks reasonably clean at a good price.
It is also important to consider how the diamond will be worn. If it will be set in a mounting that will cover the stone’s sides, then an SI2 diamond may be a good choice as whatever visible flaws it has on its sides, these inclusions will be concealed by the setting anyway.