Diamond Grading SI 1 vs. SI 2
This illustration shows a sample of the difference between SI 1 and SI 2 under 10x Magnification.
Diamond Grading SI 1 vs, SI 2: The difference between SI 1 and SI 2 diamonds may be very subtle and only noticeable to a trained expert.
For most people, the first consideration is of budget. What you may want to spend depends upon your circumstances, what you can afford. What matters most is not how much money you spend, but the feeling and intention that the diamond represents. Purchasing a diamond is a personal and intimate decision.
We recommend diamonds that are slight inclusion one (SI 1) or sometimes, if budget is a strong consideration, slight inclusion two (SI 2). Both are generally considered "eye clean". In other words, if you look at the diamond, particularly with the SI 1 and usually with SI 2, you will not see carbon spots. However, under a 10x magnification you may see noticeable inclusions. The difference between SI 1 and SI 2 is that the SI 1 diamond has fewer and smaller inclusions, which may possibly result in greater clarity. However, the difference between SI 1 and SI 2 may be very subtle and only noticeable to a trained expert.
Despite the attempt to standardize grading, there is still some variation, some subjectivity in grading. The difference between grades is sometimes a subtle judgment call. Some diamond grading labs are more conservative than others. For example, GIA will often give a lower grade to a diamond than EGL. They should be used in price/grade comparisons cautiously, or not at all. Nevertheless, many online jewelers take advantage of these differences, particularly on the internet.
The SI 2 diamond will have more inclusions at the center of the diamond
- Those issues aside, here is what you might see looking at a diamond with magnification for an SI 2. The SI 2 diamond will have many inclusions at the center of the diamond. They could also have a singular larger inclusion as shown in the image on the left.
At the most, the SI 2 may impact about 5% of the diamond reflective ability. If the diamond is well cut, this would only be noticeable to an expert. Many SI 2 gems have no difference in brilliance from a SI 1 or even higher grades, such as very very slight inclusion two (VVS 2).
The difference between an SI 1 and a VVS 2 would not be noticeable to the naked eye, but the price difference would be huge. Jewelers make a big deal over white and clear diamonds to the customer, but really the rarest of gems is most apparent only to those looking under magnification who are very sophisticated in diamond grading.
The difference between SI 1 and SI 2 diamonds may be very subtle and only noticeable to a trained expert.
Grading Is Subjective
- You can begin to understand why this issue of grading has a level of subjectivity among diamond graders and diamond buyers. Some people place high value on a near colorless shade of diamond that is clean under magnification. There is a lot of marketing around levels of clarity that appeal to those who are seeking levels of perfection in a diamond. The perfect flawless stone is definitely available when finance is not of concern.
The cut and color are also major factors in how a diamond looks. However, even a "good" cut grade can have such strong optical properties that they look beautiful. A basic SI 1 diamond that is white, which is at least in the G and H color, and good to excellent cut, will be beautiful.
Yet, even off-white colors, the cognac diamonds, which are increasingly popular and yet are considerably less expensive, are worth considering. A well cut cognac diamond is exquisite. Ultimately, what matters most is what the diamond means to you.