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January 28th 2022

The SI1 Clarity Diamonds Guide

By Devin Jones

Diamond clarity is one of the most important factors in determining your diamond's appearance, price, and desirability. If you're considering SI1 clarity diamonds then you already know, getting the most value from your diamond is a balancing act between price and quality.

SI1 clarity diamonds are great for maximizing value, but be careful that you don't choose a diamond with obvious flaws that can be seen with the naked eye. On the one hand, you don't want to overpay for quality you can't appreciate on a daily basis. On the other, you don't want to skimp on diamond clarity and purchase a diamond that is obviously "included".

Can you tell which of the diamonds below is the most included?

FL clarity diamond
IF clarity diamond
VVS1 clarity diamond
VVS2 clarity diamond
VS1 clarity diamond
VS2 clarity diamond
SI1 clarity diamond
SI2 clarity diamond

Click on each diamond for more details and videos

The diamonds shown above range from FL to SI2 in order from top right to bottom left. The SI1 clarity diamond shown above as the second to last stone has a large dark inclusion on the table.

This is one of the worst types of inclusions you could see in an SI1 diamond based on the location and size of the inclusion. If it were any larger it would definitely receive an SI2 or lower clarity grade.

It's this balancing act that leads many people to choose either an SI1 clarity or VS2 clarity diamond. We even wrote a popular SI1 vs VS2 clarity comparison to help you understand the nuances between these two grades.

Below we'll give you our honest advice on when you should consider an SI1 diamond and when you should opt for a different clarity grade to maximize value or appearance based on your specific diamonds carat weight and shape.

What Is SI1 Clarity?

Diamond clarity grades describe the size, number, and significance of the imperfections that exist inside a diamond (inclusions) as well as blemishes that appear on the diamonds surface. Some diamonds are completely flawless inside and out (FL clarity, meaning flawless) while others are completely flawless on the inside but have some minor imperfections on the outside of the stone from the cutting and polishing process (IF clarity, meaning internally flawless).

A step down are the Very Very Slightly included diamonds (VVS1 and VVS2 clarity diamonds), followed by the Very Slightly Included diamonds (VS1 and VS2 clarity). For all of the diamond clarity grades mentioned thus far, the imperfections should only be visible under 10x magnification. Keep in mind that when you're evaluating diamond images online, these images have often been magnified more than 10x and inclusions will be easy to see.

SI1 clarity means "Slightly Included 1", and is one of the most popular diamond clarity grades chosen for engagement rings and most other jewelry purchases. SI1 clarity diamonds are less expensive than VS2 clarity diamonds, but can still appear flawless to the naked eye. This perfect appearance despite the presence of some minor inclusions is what jewelers refer to as "eye clean", meaning it looks clean without the help of magnification.

While these diamonds are not considered “flawless”, the inclusions present within them can be small enough that they will not be visible to the naked eye. This often depends on which types of inclusions they are and where they are located.

Is SI1 Clarity Worth It?

SI1 clarity prices can vary significantly depending on the types and locations of each diamond's inclusions. That's why you need to be extra careful when finding a great deal on a VS2 or lower clarity diamond - if it's too good to be true, it probably is.

Some SI1 diamonds like this eye clean SI1 from Blue Nile have dark inclusions but in a favorable position where they can be covered up by a prong from your engagement ring setting. Others, like this non-eye clean diamond have a dark inclusion in the center of the diamond where it's easily visible.

Even within SI1 diamonds the price can vary significantly, which is something to be aware of when using our diamond price estimates. In a recent study, we saw that 1 carat Round H color SI1 clarity diamonds ranged in price by up to 20%.

All this is to say, determining whether an SI1 diamond is worth the price is not a simple question - you must take into account the severity and location of inclusions as well as the price. The very best SI1 diamonds can cost as much as VS2 clarity stones, while the worst may look like an SI2 clarity.

None of this is meant to steer you away from SI1 clarity diamonds. However, if you are shopping for an SI1 clarity diamond you should consult with a professional either via the chat or telephone options listed on most top online jewelers or in person at your local jeweler. Local jeweler margins tend to be higher than online jewelers, so you can expect to pay more for the opportunity to see the stone in person before purchasing.

We'd also recommend you consider moving up to a VS2 clarity diamond if you're purchasing online, since the cost savings from buying on the internet may allow you to improve the clarity grade of your diamond for the same price you'd pay in person. Generally speaking, VS1 and VS2 clarity diamonds are the most popular grades for online diamond shoppers, while local jewelers then to sell more SI1 and SI2 clarity diamonds.

Part of this boils down to the fact that diamonds don't look as included in person as they can appear in images you see online, due to the magnification. Most people struggle to notice inclusions with the naked eye unless they are dark inclusions on the top of the diamond. For more guidance on the worst types of inclusions and how to pick out an eye clean diamond, check out our eye clean diamonds guide.

SI1 diamonds are still within the range that jewelers typically recommend to their clients (basically grades from SI1 to VS1), as the imperfections can be too small to be seen by the human eye. StoneAlgo typically recommends that you target a VS2 clarity diamond to begin with when buying a stone and make sure to view images and videos of any diamond you plan on purchasing. The difference between SI1 and VS2 diamonds is a major consideration for many diamond buyers.

Which Diamond Shape Is Best For SI1 Clarity?

Some diamond shapes can help you hide your inclusions more easily than others. For example, a round shape diamond will hide inclusions more easily than a fancy shaped diamond with larger facets (such as princess cut diamond). That said, fancy shapes cost far less than round diamonds and you can likely afford a higher clarity grade in a princess or asscher cut diamond than you would in a round diamond.

Take these below SI1 clarity diamonds in various shapes for example. Notice that the round diamond has a smaller table (the flat part of the diamond in the center) than the princess cut and other fancy shapes have. The round diamond also maximizes the sparkle of the diamond which helps to distract from any inclusions that might otherwise be visible.

SI1 clarity round diamond
SI1 clarity princess diamond
SI1 clarity oval diamond
SI1 clarity emerald diamond

Click on a diamond for more details and videos

Which Diamond Color Grade Is Best For SI1 Clarity?

Most diamond shoppers who are considering SI1 clarity tend to be pretty savvy at evaluating the tradeoffs between price and appearance. They are looking to maximize value, so it's no surprise that these same shoppers steer clear of the highest and most expensive color grades like D color diamonds.

The most popular color grades for SI1 clarity diamonds are G color, H color, and F color which make up the majority of all SI1 clarity diamonds searched for in StoneAlgo's popular diamond search engine. Here are all of the color grades ranked by popularity for SI1 clarity diamonds:

  1. G Color SI1 Clarity Diamonds (20%)
  2. H Color SI1 Clarity Diamonds (16%)
  3. F Color SI1 Clarity Diamonds (15%)
  4. J Color SI1 Clarity Diamonds (15%)
  5. I Color SI1 Clarity Diamonds (11%)
  6. E Color SI1 Clarity Diamonds (11%)
  7. D Color SI1 Clarity Diamonds (10%)
  8. K Color SI1 Clarity Diamonds (4%)

For more details on diamond color and clarity grades including pricing, check out our awesome tools like our diamond price calculator and diamond price charts. If you've already found a diamond you love, run it through our 100% free GIA check tool to see the fair price and learn about the diamond's visual carat weight.

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