What Are SI1 (Slightly Included) And SI2 Diamonds?

SI1 and SI2 diamonds are slightly included diamonds that contain some physical blemishes. As a result of this, they dwell at the bottom of the diamond clarity grading scale. SI1 and SI2 inclusions are often easily seen by the naked eye.

SI1 vs SI2 diamonds
An SI1 diamond (left) versus an SI2 diamond (right)

Clarity is only one facet of the 4C’s of diamond grading, the others being cut, color, and carat.

Even with inclusions present, it still doesn’t mean that an SI diamond loses all appeal. They are much less expensive compared to their high-achieving Flawless and Very Very Slightly Included counterparts. Inclusions can be thought of as birthmarks that are acquired during a diamond’s underground, high-temperature, long-term growth. They make each diamond one of a kind.

How Is Diamond Clarity Measured?

Each diamond’s clarity grade is usually measured by multiple professionals with the help of a jeweler’s loupe. A jeweler’s loupe is a small magnification device. 

There are multiple inclusion types, and their nature, color, and dimensions help to determine a diamond’s clarity grade. Here are a few common types of inclusions:

  • Pinpoint Inclusions – tiny black dots on the surface of the diamond.
  • Feather Inclusions – internal cracks in the diamond.
  • Cloud Inclusions – Hazy areas where multiple pinpoints are located.
  • Twinning Wisp Inclusions – Streaks formed out of a series of clouds, pinpoints, and/or growths of crystals. They can be thought of as thin, gemological banners, where multiple inclusions have twisted together.

Should I Buy An SI1 Or SI2 Diamond?

SI diamonds are a great money-saving choice that can still deliver in looks. However, if you are purchasing a step cut diamond such as an emerald cut diamond or an Asscher cut diamond, you should avoid diamonds with SI1 and SI2 clarity grades. Step cut diamonds have a large, open table, making imperfections easy to spot. Brilliant cut or modified brilliant cut diamonds, such as round cut diamonds, princess cut diamonds, and oval cut diamonds are much better at concealing inclusions.

si2 diamond comparison
An SI2 emerald cut diamond versus an SI2 oval cut diamond

You can hide diamond inclusions with the right setting depending on their location. Prong settings and bezel settings are excellent at hiding inclusions.

Where Can I Find SI1 And SI2 Diamonds?

SI1 and SI2 diamonds can be purchased online or in jewelry stores. If you’re buying any kind of diamond online, it’s important to view HD images and/or videos of the diamond before purchasing. Because SI1 and SI2 diamonds aren’t always eye clean, you may want to see your diamond in person for extra assurance before purchasing it to make sure you are happy with it. Take advantage of our Free In-Store Preview program to view your diamond at a local jeweler at no cost.

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