Premium Size Diamonds: Diamonds at a Smarter Price
Have you ever dreamed of owning a large, high-color, high-clarity diamond — only to find that your budget falls just short? Many savvy diamond buyers have found a clever workaround: looking for a stone with the same color and clarity grades but slightly lower carat weight. The price difference can be staggering, sometimes hundreds of thousands of baht.
A Tale of Two Diamonds
Consider two round diamonds with identical specs — both D color, VS2 clarity, and 3EX cut — but different weights. The first weighs 0.35 carats and the second weighs 0.40 carats. That difference is just 0.05 carats, or 5 points. To the naked eye, they look virtually the same size.
Yet when you check the prices, the 0.35 carat diamond is priced at approximately 75,200 THB, while the 0.40 carat diamond jumps to around 90,900 THB — a difference of 15,700 THB, or roughly 18% more. For nearly identical-looking stones, that is a significant premium to pay.
Why Does This Price Gap Exist? Enter: Rapaport
To understand why, we need to look at the Rapaport Price List (the globally recognized diamond pricing benchmark), which is quoted in US dollars per carat (USD/carat). Rapaport groups diamonds into carat weight ranges, such as 0.30–0.39 carat, 0.40–0.49 carat, 0.50–0.69 carat, and so on. Each range has its own price-per-carat rate, and the ranges are not equal in width.
To calculate the actual price, you add two zeros to the listed figure. For example, if the table shows 198, the real price is USD 19,800 per carat — multiply by the exchange rate (roughly 31 THB/USD) and you get approximately 621,324 THB per carat.
The key point is this: a 0.35 carat diamond and a 0.40 carat diamond fall into different Rapaport weight brackets entirely. The 0.35 carat stone is priced using the 0.30–0.39 carat rate, while the 0.40 carat stone uses the higher 0.40–0.49 carat rate. In other words, the moment a diamond crosses into a new weight bracket, its price per carat jumps — regardless of how small the physical size difference actually is. However, keep in mind that the discount from the Rapaport price might be more for a 0.40 carat diamond than a 0.35 carat diamond.
This is similar to how gold is priced: 99.99% pure gold (24K) commands a higher price per unit than 96.5% gold (23K), even if the physical pieces look alike.
So, What Exactly Is a "Premium Size" Diamond?
A Premium Size diamond is one that sits at the top end of a lower Rapaport weight bracket — close in size to the next bracket up, but priced at the lower bracket's rate. These stones are relatively hard to find, but they offer exceptional value.
Common premium size ranges include:
0.35 – 0.39 carat
0.45 – 0.49 carat
0.60 – 0.69 carat
0.80 – 0.89 carat
0.95 – 0.99 carat
1.30 – 1.49 carat
1.80 – 1.99 carat
For example, in the 0.90–0.99 carat bracket, the premium size range is 0.95–0.99carat These diamonds look almost indistinguishable from a 1-carat stone — but the price has not yet crossed into the 1 carat bracket.
A Word of Caution
That said, seeking out premium size diamonds is not the only strategy for getting great value. Cut quality, stone proportions, and many other factors also play a major role in a diamond's beauty and true worth — all topics that Calette will be covering in future posts.
Looking for round or fancy-cut GIA-certified diamonds? Reach out to us at info@calettediamonds.com or Line: @CaletteDiamonds
