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SI2 vs SI1: How Different Are These Clarity Grades?

Learning all the lingo that goes along with shopping for a diamond engagement ring can seem like learning a foreign language. There are so many different clarity grades — ranging from FL to I1 — that it’s difficult to know what to look for (and what to stay away from).

Diamond clarity grades can be a bit controversial, too — especially when you go down the scale. One of the most debated grades? SI, or slightly included diamonds. Let’s break down the differences between the SI2 vs. SI1 clarity grades to help you figure out if it’s the right pick for diamond engagement ring.

SI2 vs SI1: What's the difference?

Both SI2 and SI1 clarity diamonds have inclusions that you might be able to see with the naked eye — some big, some small — and can be seen on the center or sides of the stone near the girdle. The biggest differences in the SI2 vs SI1 debate are the number and type of inclusions they have.

si2 vs si1 comparison zoomed out

SI1 diamonds tend to have fewer inclusions than SI2 — as few as one inclusion, to several in the same stone. The inclusions tend to be smaller and can range from crystals to feathers, knots, needles, cavities, chips, clouds, twinning wisps or indented naturals. (Wondering what the heck all those terms mean? Check out our guide to diamond inclusions to find out more and see examples of these types for yourself.)

SI2 diamonds, on the other hand, will have the same types of inclusions as SI1 diamonds, just more of them. They tend to be larger, too.

si2 vs si1 comparison zoomed in

As for their looks? Well, that depends on the actual stone. As you can see, there isn’t always a huge difference in appearance when it comes to SI2 vs SI1 diamonds. One might appear foggier or have a less-than-perfect appearance when compared to the other, but the typical ring admirer probably won’t be able to tell the difference in the shine between the two.

SI2 vs SI1: How their prices stack up

The biggest upside to an SI diamond is the price. SI1 diamonds are just a grade below a Very Slightly Included 2 diamond, meaning they’re very similar — but with very different prices. Typically, an SI diamond will save you anywhere from 10 to 20 percent over a VS diamond.

You will also see a price difference when you compare an SI2 vs SI1 diamond, but the actual difference depends on the actual stone itself.

Are SI diamonds a good choice? The bottom line

Simply put, SI clarity diamonds should be evaluated on a case by case basis for your diamond engagement ring. We’ve seen some gorgeous SI diamonds before. But we’ve also seen, and advised customers against buying, some SI diamonds that definitely weren’t ideal for brilliance.

If you want to invest in SI diamond, it’s best to work with a gemologist who can help you find the best stone with the fewest inclusions. An expert gemologist can also help you pick a diamond engagement ring setting that’ll help mask any inclusions that take away from the beauty of your stone.

Still interested in an SI diamond but don’t know where to start? Fill out the short form below and we’ll have our experts hunt down three personalized diamond suggestions that fit your tastes and budget. Like one? Wonderful! We can chat from there. None of them fit? Tell us. Our experts want you to be happy, and they’ll go back to the drawing board to hunt down that perfect fit.


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