Everyone knows that the bigger the diamond the more it costs. But not everyone understands why.

We buy diamonds much like you do fruit...by  weight. Instead of pounds and ounces, we use carats and points. (Points are a measurement of weight, not to be confused with the facets on a diamond.)

One carat consists of 100 points. (Written 1.00 cts.) A half-carat would be written .50 cts., etc.. (cts = points)

Not every diamond weighs to be an even fraction ( .25, .50, .75 etc.) and so we round off the categories.

When we buy diamonds we pay so many dollars per point. As size increases (rarity) the price per point increases. The combination of increased weight and price per point creates an exponential increase in price. Example:

As we see size go up, price escalates at a higher rate. This is why a ring with 1/2 ct. total weight (made up of 10 stones) sells for a lot less than a single stone of 1/2 ct. weight. The smaller stones are not  worth near as much individually (per point), therefore there combined value is also less.
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So, why is it we find such a difference in prices for the same size category of diamond when the clarity, color, and cut are equal? It's a secret most customers don't understand. The price we pay per point for diamonds goes up as the size does, but is not consistent with the carat categories above. It seems in the free market size catagories are broken down even further. For example, gemologically, a 1/2  carat diamond is from .45 cts to .55 cts. However, when we purchase diamonds we break 1/2 carat diamonds into three price catagories. Diamonds weighing .45 cts are priced with the 3/8 cts. Diamonds weighing from .46 to .49 cts are in a seperate catagory. Diamonds weighing .50 and above are in a third. The difference to jump from a .49 cts. diamond to a .50 cts. diamond can easily be $400 or more (wholesale) based soley on weight. (To go from a .48 to .49 might be $45; .50 cts is the breaking point, and an expensive one.)

What does that mean in simple terms? If I'm a jeweler selling a 1/2 ct solitaire for $999 and want to maximize profit, I will sell a .45 cts - .49 cts diamond. I will not be able to sell a .50 cts for that price. When one is shopping for a 1/2 ct diamond, it isn't a fair comparison to price a .48 cts diamond with a .52 cts diamond. It's like comparing apples and oranges.

So, how does this help you? Here are some secrets:

Want a 1/3 ct. - buy a .29 cts. and save a lot.
Want a 1/2 ct. - buy a .45 - .49 cts and save a lot.
Want a 3/4 ct. - buy a .69 and save a lot.
Want a One Carat - buy a .90 - .95 and save a ton.

( You won't find many .98 cts or .99 cts. because cutters aren't stupid. They will keep that little extra rough on the stone to have it weigh in at the magic 1.00 cts. Read about weight saving in our area on Cut)

After 1.00 cts  the breaking points are every 50 points - or - 1.50 cts, 2.00 cts,
2.50 cts, etc..