I read all the Diamond Buying Guides, so you don’t have to

How to buy a great diamond ring

Diamond Engagement Ring

I spent last year studying diamond buying, as part of my effort to buy a proper diamond engagement ring. This led me from knowing nearly nothing about diamonds to feeling fairly-well educated on what matters. Here are my conclusions and advice.

Note this article is about traditional diamond engagement rings, in the traditional, round style, since that’s what I was interested in. There are a few caveats for the fancy styles, but the basic advice is about the same (be sure to research further if you are looking at other styles).

Starting out, I was very confused about what was important when buying a diamond, and the prices were scary, especially for larger stones. Sure, we all hear about the 4-Cs, and there are great e-commerce websites like Blue Nile, James Allen and Brilliant Earth, but they don’t really help you choose nor focus on what matters, usually leading to overspending for less-than-ideal stones.

Bottom Line, Up Front

Most people are spending too much on diamonds, typically because they are focused on the wrong things, are buying too far up the wrong scale, and throwing money away. Or, they just can’t easily evaluate what a vendor (usually a jeweler) is showing them.

So I’ve broken down a rough summary for three spending levels, which you can use to just buy off reputable e-commerce sites like Blue Nile or James Allen.

For the options below, choose these three Cs (Cut, Color, Clarity) as specified, and then the Carat size you can afford, and you are done. Note in my list below, I give two color grades, the first (GHI) is for white gold rings, while the second (IJK) is for yellow gold rings. Also, these are GIA-based grades; you’ll usually want to go up a single level in each category for lesser rating firms.

Budget — For the very cost-conscious, or for whom the stone’s amazingness is less important (i.e., they just want a basic ring), select a Very Good Cut, I/K Color, SI1 diamond, about a half-carat or so. It won’t be a fantastic stone, but it will be a solid value & actually probably better than many folks end up with. These run about $750–850; see examples at James Allen.

Moderate — Most people can get excellent results at reasonable prices with an Excellent/Ideal Cut, H/J Color, VS1 diamond that’s between 0.5 and 1 Carat. The price and the stone will both be very good. These are $1000-$1200, with these examples.

Generous — To get an amazing stone on a healthy budget, combine an Excellent/Ideal or Vendor’s Top Cut with Hearts & Arrows-level Symmetry, G/I Color, and VVS2 Clarity. This level of cut will give you a stunning stone that simply cannot be improved at any price, and yet still saves money. See examples.

The observant reader will note that while I suggest the best cuts possible, I don’t recommend above a G color and VVS2 clarity as above those levels is simply not worth the price(in fact, H & VS1 are likely the best you’ll ever need). Spend money on the Cut — really work hard on that — then on the Carat weight you want.

The 4-C’s

Everyone prospective diamond buyer should be familiar with the 4-Cs: Carat, Cut, Color, and Clarity. They are important, but not necessarily in the way you may think, and advice on some of them is very murky at best.

The rules are really simple.

Focus on Cut first, then choose Color and Clarity based on basic guidelines, and finally select the Carat weight you can afford. In that order. That’s it.

Focus on Cut, Color, Clarity, Carat, in that order.

In real estate, all that matters is location, location, and location. In diamonds, one can argue that all that matters is Cut, Cut, and Cut. Do not forget this. If there is one thing to spend money on, it’s Cut — period.

Cut

Why the focus on Cut first? Because that’s what people see, and it’s what makes a diamond shine and sparkle like, well, a diamond.

Generally, you want to spend extra money on the Cut first, then choose the Carat size your budget allows; do not do the reverse or you’ll get a big dull rock (plus, a well-cut smaller diamond looks bigger anyway).

Cut Basics

Cuts have confusing names, but the GIA “Excellent” or AGS “Ideal” are the top Cuts. However, many websites then have their own branded “even better” Cuts, such as Blue Nile’s “Astor Ideal” or James Allen’s “True Hearts”, both of which theoretically offer the finest Cuts you can buy.

When shopping on line, start with the best Cut the seller offers, such as the Astor Ideal or True Hearts, then set Color & Clarity as noted below, and adjust the Carat to your budget. That’s the simplest way to get the best diamond.

Note that for a GIA Report with Excellent Cut, also ensure you have Excellent Polish & Excellent Symmetry. Never settle for less than the best in all areas of a Cut report.

Advanced Cut Concepts

To go beyond the simple website or rating Cut selectors like “Ideal”, there are two additional steps you should take if you are motivated and want the very best light performance. These can greatly enhance even the smallest stones.

1 — The first evaluation is known as Hearts & Arrows, which uses a special viewer to see if the stone is really symmetrical and cut correctly. Many of the top websites like James Allen have Hearts & Arrows images for most diamonds, while other sites can often provide them on demand. Many sites show you how to read these images.

If you are in a jewelry store, you should bring your own IdealScope viewer, as stores rarely have them (maybe they don’t want you looking too closely at their diamonds?) There are online guides on how to use these viewers, and what to look for when examining stones.

2 — You should get the Diamond’s cut details, especially the percentages and cut angles, as these are what really affect the diamond’s light performance. This is a complicated area, but well-worth your time if you want the very best cut diamonds.

Some sites provide these numbers directly, as do some grading reports (GIA reports should have this). For websites that don’t have Cut details, you can often request the site to hold a diamond or two for you while they send you both the Hearts & Arrows images and the Cut details.

For the very best Cut proportions, ensure your diamond has the following percentages & angles, though note they are approximate, as different sources have slightly different numbers. It’s better to be in the middle of these ranges:

  • Table: 53–58%
  • Depth: 61–62.5%
  • Crown Angle: 34–36%
  • Pavilion Angle: 40.6–41%
  • Lower Girdle: 75–80%
  • Girdle Thickness: T-M-ST (Thin/Med/Slightly-Thick)

The excellent Beyond4Cs website has a good guide on these ratios.

Color

Color is pretty easy, graded on a D-Z scale, with D being the “best“ or colorless. It’s VERY easy to overspend on Color, so it’s critical that you choose the right Color so you can save money to spend on Cut and Carat.

Plus, great Cut will mask many small Color issues, by allowing the bright light performance will shine through, further allowing you to go down the Color scale and save money.

Be aware that larger stones will show more Color, so above 1 Carat, you might go up one Color rating, say from a H to G or K to J.

Optimal Diamond Color Depends on the Ring Color

The key question on diamond Color is the Color of the Ring Setting, as this makes a big difference. Common choices are White Gold & Yellow Gold.

For the popular White Gold settings, you want a fairly colorless Diamond that will look white and shiny in its white setting. For this, choose a G or H nearly colorless Diamond. The higher D-F grades are very expensive & not worth it.

For the Yellow Gold setting that I personally prefer, Color is much less important, as the yellow in the ring will add yellow to the diamond, so any high-Color diamond like D or F will be totally wasted. Instead, choose a J or K Color diamond, and save a lot of money.

Clarity

Clarity is also an easy choice, and another area where you can waste money. It’s graded from IF (Internally Flawless) to VVS1-2 (Very Very Slightly Included), VS1–2 (Very Slightly Included), SI1 (Slightly Included) and then the lower grades. “Inclusions” refer to flaws that affect light performance.

Generally choose a VS2 diamond, and maybe VS1 for larger stones over 1.5 Carats (though try to get VVS2 for non-GIA graded diamonds). You can get away with an SI1 as a budget choice, especially if you can see a good Hearts & Arrows image to make sure the inclusions don’t affect light performance.

Carat

Most people care about diamond’s weight, which after the Cut, Clarity and Color, is the next & final thing to think about. People will generally buy the weight that fits their budget and goals, keeping in mind that bigger is not always better, especially in larger stones.

Diamond prices rise sharply as the stone gets larger, and prices also jump at the 0.5 weights, especially at 1.0, 1.5, and 2.0 Carats. You’ll usually find 0.9, 1.4, 1.9-carat rocks are very good values without losing any real size.

My general thoughts on Carats are as follows:

0.5 Carat — This is the typical the base diamond that most people think of and nearly everyone can afford. It’s a good size for those with limited budgets or who want a basic ring for its tradition and meaning, though 0.75 Carat is more substantial-looking. Go to a jeweler or diamond mart and take a look at this and other sizes. By following the other guidelines here, you can get very bright and pretty diamonds for very reasonable prices.

1.0 Carat — The 1-Carat diamond makes a very nice ring and is a very good weight without breaking the bank. It’s a good goal for most people who have decent paychecks. By getting a great cut, you can get amazing-looking stones that are both pretty & practical.

1.5 Carat — For those looking to go up in size a bit and spend more, the 1.5 Carat stone is very nice, but not ostentatious. With a very nice Cut, these can be very noticeable and impressive, in a good way. Also, above this weight can look large on smaller fingers, and will leave a much larger hole in your wallet. That said, there are many very nice & affordable stones in the 1.75 range.

2 Carat — A 2-carat stone is very impressive but is at the edge of budget and reasonableness for most people. Depending on the setting, this weight and above can be quite tall and easy to knock into things. Plus this size begins to border on being too large for many people.

2+ Carat — These are big diamonds, with sizable price tags and only exist to really say “look at me”. If you are buying these, be really sure to try on samples and understand the practical realities of a ring this size, including the importance of a low-height setting to avoid hitting it on everything. Of course, if you’re spending $25-50,000 for a diamond, you probably aren’t reading this guide (but you should).

Lab-Grown Diamonds

We’ve mined diamonds from the Earth for thousand of years, but recently lab-grown diamonds have come on the scene. They have two key advantages: price & source. They often cost 40% less than natural diamonds — this is a huge savings that can dramatically affect what you can buy. Websites like Brilliant Earth are leaders in this area (and is where I bought my diamond) and popular sites like James Allen now offer these, too.

Lab-grown diamonds also, by-definition, cannot come from conflict zones, nor involve slave labor, nor create pollution or other problems in source countries (of course they also don’t contribute to jobs in those areas, either).

These lab diamonds are quite new and their resale value is certainly lower, plus GIA won’t grade them, so you are left with 2nd tier reports. However, as long as you pay attention, these are great diamonds at great value.

Personally, I bought a beautiful lab-grown diamond for half the price of a natural stone. And by focusing on the other factors in this article, I ensured it was both the very best value and nicest diamond I could possibly purchase.

Summary

That’s it. Follow this simple guide or dig in a bit deeper, but diamond buying shouldn’t be all that scary, even with real money at stake. Focus first on Cut, make good choices on Color and Clarity, then get a Carat weight that works for your wallet — you’ll be very happy with your choice.

For more info and the best site I found on-line, see the Beyond4Cs site, run by the exceptionally knowledgeable Paul Gian in Singapore.

Sites I liked for buying: Brilliant Earth, James Allen, Blue Nile.

I’m Steve Mushero and I have no connection to the diamond industry at all. But as an engineer & entrepreneur, I found the process and knowledge fascinating, and I’m pleased to be able to share it with you, too. Feedback is welcome and I’ll update the article from time-to-time.