I compare Costco (and other) diamond rings and jewelry based on the data. I only compare to trustworthy retailers. Is that Costco diamond you’re looking at worth it? In today’s comparison, I look at this Square Emerald Cut 1.98 ctw VVS2 Clarity, F Color Diamond Platinum Engagement Ring. (It’s available at time of publication. Because it’s a single-item offer, the diamond being unique, it can go out of stock at any time.)
However, that’s not true of the James Allen offer. You can always build the ring I show you how to build at James Allen. (See the table of contents to find the directions on how to build it.) Why? Because at James Allen you have an enormous number of diamonds in inventory to choose from.
Quick Links to Contents on This Page
Bottom line of this price comparison: James Allen is $650 less
You’ll save $650 by buying a diamond ring with the same specs at James Allen. (You even get to know the specs of the accent diamonds at James Allen.)
To see how easy it is to build the ring at James Allen, scroll to that easy section below.
Now, if you want to see the data and specs laid out quickly, let’s dive in.
Costco’s offer: $16,999.99
It’s Costco item number 955883, for those following along at home.
Costco Diamond’s GIA Diamond Grading Report
A 3rd-party lab-issued diamond grading report is simply expected for any even mildly expensive diamond. This diamond is about $17K, so it’s completely expected.
You can read the diamond grading report by looking it up using the report number at the GIA site. (Be warned, for some reason these sometimes don’t load in Chrome, especially if you’re using a VPN. But these reports are generally available and will work in Chrome, Firefox, or Safari.)
Costco Diamond’s Shape
That shape is often called a Square Emerald. It’s also more properly known as an Asscher Cut. Either way, it is what it is: A beautiful cut for a transparent diamond. This shape does not emphasize sparkle. It emphasizes clarity and depth. That’s a different kind of beauty than most people look for in a diamond (most people prefer to maximize the sparkle, fire, and brilliance, using a brilliant shape such as a Round Brilliant or Cushion shape.
Carats of the Costco Diamond
It’s listed as 1.98 ctw, which of course stands for carats total weight, and in plain English means “The total weight of all the carats of all the diamonds on this entire ring.”
The center diamond, we’re told, is 1.80 carats.
The total carat weight of all the diamonds is 1.98.
So we just do the math: the accent diamonds total up to 0.18 carats. (This will be relevant when we compare prices at a major, trusted diamond jewelry retailer later on in this article. We’ll compare apples to apples, so to speak. A similar or same design of ring with similar or same carat weight of accent diamonds and center diamond.)
Clarity is VVS2
That’s important for this shape of diamond. You want quite high clarity for any diamond that is step cut. This is a “square emerald” cut. (A plain “emerald cut” is rectangular, not square.) It’s otherwise known as an Asscher cut. It’s designed to show off a diamond’s clarity, rather than to make the diamond sparkle as much as possible.
Color is F
An exceptional color grade such as F is important in this cut, as well, Because the Asscher Cut shows off a diamond’s inner beauty, people will be able to see the color easily. (Color and clarity can be obscured in a cut such as the Round Brilliant, which sends so much sparkle and fire up through the top that it’s sometimes hard to see the color and clarity.)
Quick note, because even many experienced shoppers don’t know, or forget: there is no A, B, or C grade of color. The best possible color is D. Before the GIA created this scale, jewelers’ abused a supposed scale of color. Calling anything and everything A, B, or C. So those definitions were just too tainted to use. So, the GIA scale wiped the slate clean by starting with D as the best possible color.
The metal of the setting is Platinum
Platinum will last forever. It gets a patina, but these microscopic scratches (that’s what we see as a patina) can be easily polished back into the platinum. It never need replating, as does “white gold”, which has a Rhodium plating that wears off every couple of years.
Always note: if you need resizing, you’re on your own, with Costco. (See the image of course.) Compare that to James Allen’s ring resizing guarantee, for example, where they’ll resize your ring for free for up to a year.
Now James Allen’s offer: $16,350 for a 10% larger center carat diamond (2.01 carats). All other specs are identical.
Every data point on this James Allen ring is the same, except for the carats. It is 10% larger. (I didn’t find in James Allen’s inventory at the time of writing a diamond of exactly 1.80 carats, or between 1.80 and 2.01.)
The accent diamonds are even graded at James Allen. Here’s why that’s a huge advantage.
Accent diamonds aren’t an afterthought, of course. They are a key design element of the ring.
If you get accent diamonds that are too far down the color scale, you risk messing up the effect of the ring. It’s like the wrong color shoes with a suit. Seems like it shouldn’t matter, but it really does. You don’t want over-yellow diamonds ruining the effect of an F color (which is a very good color grade, indicating a high level of transparence).
That’s why James Allen specifies the color of the accent diamonds. They range from G to H.
Costco doesn’t specify what color or color range will be in the accent diamonds. That’s a risk, in my opinion. What if you get accent diamonds of a color grade that you don’t really love? It’s better to be able to know the specs, know the data before you buy.
How to build a ring like this at James Allen, and save $650 or more:
It’s easy.
- Select this platinum ring setting. (It’s the ring only, with the accent diamonds included, but not yet the center diamond. You’ll select the center diamond in the next step.) It’s SKU 17645P.
- Then go to the James Allen diamond inventory search / selector. And simply set your slider as shown in this image, below: (By the way, that link may preset all the sliders for you! I’ve been experimenting with coding the links so that they’ll do that. But if that doesn’t work, then just manually adjust your sliders as shown in the image below.)
Every diamond at James Allen is unique. You select your setting (the ring itself). Then you select the exact diamond that you want.
From here on out, it’s easy. You can see the first four diamonds that the search engine found currently in inventory there. You select a diamond that you like. You double check that the specs match what you want. You examine it to your heart’s content using James Allen’s groundbreaking 3D exact imaging of your exact diamond.
Then you add the setting and add the diamond. That’s it! You’ve built the ring.
The only reason the Costco diamond ring may be worth it after all
If you need the engagement ring fast, then the Costco premium of price (and mystery as to the accent diamonds’ color grades) may be worth it. The Costco ring is ready to ship.
But if you have more time. If you’re planning your proposal well in advance. Then the Costco ring is not worth it, in my opinion, because with James Allen, you get a 10% larger center diamond, you get to know the color range of the accent diamonds, and you save $650. (All the other specs are the same or arguably better.)
Enjoy your shopping. You got this.
It’s easy to get great deals on better diamond jewelry — for less money! Here’s how:
- Scroll up to the section on “How to Get the James Allen Deals.”
- Follow the easy directions there.
- Feel 100% confident that you bought the best diamond for the money
How to search this site to save up to tens of thousands of dollars at trusted diamond retailers, vs most any Costco, Kay, Jared, or Zales ring you’re considering
Search and save. You could save enough for a new compact car. Or a honeymoon. Or several expensive dinner dates. Or that guitar you’ve been wanting.
Read this very short note on how easy it is.
