What ratio of center stone to accent diamonds is best for a three stone ring?
Dear Lesley, my girlfriend and I have been shopping for diamond engagement rings for awhile now, and she is definitely gravitating towards the Brian Gavin Trellis 3 Stone Ring in Platinum, but we can’t seem to agree on what constitutes the best balance between the center stone and the accent diamonds. She seems to prefer accent diamonds which are on the smaller size, while I think that the ring looks more balanced when the side diamonds are about half the size of the center stone, which we prefer to be around 1.50 carats, colorless, and VS or higher in clarity. What are your thoughts and recommendations? – Lawrence W.
Regardless of what your preference is in terms of what appears to be the most visually appealing balance between the size of the center stone and the accent diamonds, we custom make every Trellis 3 Stone Ring to fit that specific combination of diamond sizes.
How to calculate the ratio of center stone to accent diamonds:
The most common combination of sizes for three stone rings consist of accent diamonds which are either half or one third the size of the center stone, but occasionally somebody will prefer that the accent diamonds be on the larger side, such as three quarters the size of the center stone.
The formula for calculating the ratio of center stone to accent diamonds for a three stone ring, is determined by dividing the average outside diameter of the accent diamonds by the average outside diameter of the center stone.
To calculate the average outside diameter of the diamond, add the first two measurements which represent the distance across the diamond from north to south and east to west, so using this 1.551 carat, E-color, VS-1 clarity, Brian Gavin Signature round diamond as an example, the outside diameter of the diamond measures 7.43 + 7.47 = 14.9 and then divide that number by 2 = 7.45 mm as the average diameter. To determine the ratio of the center stone to the accent diamonds, we would divide the average diameter of the accent diamonds by 7.45 mm.
Example of 3 Stone Ring with accents half the size of center diamond:
In your initial inquiry, you indicated that you prefer the look of a three stone ring where the accent diamonds are about half the size of the center stone, based on your indication that you’re looking for something like the 1.551 carat, E-color, VS-1 clarity, Brian Gavin Signature round diamond, I assume that you therefore prefer that the accent diamonds weigh about 0.75 carats each, which would have an average outside diameter of 5.8 mm, resulting in a ratio of 0.77% which is represented by the picture featured to the right.
Example of 3 Stone Ring with accents one third the size of center stone:
It sounds like your girlfriend prefers something like the ring pictured to the left, which features accent diamonds which are about a quarter to one third the size of the center stone. With that in mind, I’m going to recommend you purchase the 1.551 carat, E-color, VS-1 clarity, Brian Gavin Signature round diamond and set the Trellis 3 Stone Ring with this matched pair of thirty point, E-color, VS-1 clarity, Brian Gavin Signature rounds, because this will provide her with the sense of balance she is looking for in a ring.
By the way, this combination of diamonds results in a ratio of 58% between the size of the accent diamonds and the center stone used for this particular three stone ring… therefore you can both be happy depending on how you choose to interpret the math. From one perspective, your girlfriend can be “absolutely right” because the third of a carat diamonds provide the perfect balance of being on the slightly smaller side. And from another perspective, they are 58% of the average diameter of the center stone, thus they are more or less half the size of the center diamond.
Of course I realize that I just cracked open a huge can of worms for the two of you to debate… should the size of the accent stones in a three stone ring, be determined by the carat weight, or outside diameter? Enjoy!
