13 Carat Diamond Tennis Necklace 18K Gold
A custom 17-inch tennis necklace that carries about 13 carats of lab-grown diamonds in warm 18k yellow gold, finished with a seamless diamond clasp so the circle of light never breaks — here is how this made-to-order piece comes together.
Choice one — about 13 carats: 2.9 mm round brilliant lab-grown diamonds in 18k yellow gold with a continuous diamond clasp.
Prefer even more presence? Here is the same design built with larger 4.5 mm round brilliant diamonds — about 30 carats total — shown for comparison so you can see the two side by side.
Choice two — about 30 carats: larger 4.5 mm round brilliant lab-grown diamonds, same 18k yellow gold and seamless diamond clasp.
A continuous river of light
The classic tennis necklace earns its place in a jewelry wardrobe for one reason: an unbroken line of matched round brilliants that catches light from every angle. This custom commission takes that idea to its natural conclusion. Set in rich 18k yellow gold and sized to a versatile 17 inches, it rests just below the collarbone and doubles as both an everyday statement and a black-tie centerpiece.
Each diamond is a round brilliant of about 2.9 mm, hand-matched for size and sparkle so the eye travels the entire strand without a single stone standing out of step. The result is roughly 13 carats of total diamond weight worn as one fluid ribbon.
Two sizes to choose from
This design is offered in two weights. The first is about 13 carats total in 2.9 mm round brilliants — a refined, everyday line. The second steps up to larger 4.5 mm round brilliants for about 30 carats total, a true statement piece with noticeably bigger diamonds all the way around. Both use the same D–F color, VS1-or-better, ideal-cut lab-grown diamonds and the same seamless diamond clasp.
The details
Metal: 18k yellow gold
Length: 17 inches
Stones: lab-grown diamonds, round brilliant cut
Diamond size: about 2.9 mm each (13 ct option) or 4.5 mm each (30 ct option)
Diamond quality: D, E, F color · Ideal cut · VS1 clarity or better
Total carat weight: about 13 carats or about 30 carats
Clasp: seamless continuous diamond clasp, with diamonds set directly on the closure
Why the seamless diamond clasp matters
On most tennis necklaces the clasp is the one plain spot — a small metal box that interrupts the run of stones at the back of the neck. This piece is built differently. Diamonds are set directly onto the clasp itself, so the sparkle continues without a visible break. Turn it, layer it, or wear the clasp to the side, and the necklace still reads as one seamless circle of light.
Lab-grown, ideal cut, D to F color
Choosing lab-grown diamonds lets the carat weight go further while holding a very high standard: D, E, F color sits in the colorless range, VS1-or-better clarity keeps every stone eye-clean, and an ideal cut is what actually drives the brilliance you see in the videos above. Chemically and optically these are diamonds in every sense — grown rather than mined, and graded to the same scale.
Frequently asked
Are lab-grown diamonds real diamonds?
Yes. Lab-grown diamonds have the same carbon crystal structure, hardness, and fire as mined diamonds. They are graded on the same color, cut, clarity, and carat scale — the only difference is origin.
What is the difference between the 13-carat and 30-carat versions?
Both are the same design in 18k yellow gold. The 13-carat version uses 2.9 mm round diamonds for a refined line; the 30-carat version uses larger 4.5 mm round diamonds for a bolder, higher-impact look.
What makes the clasp seamless?
The diamonds are set directly onto the clasp, so there is no plain metal gap. The line of stones continues all the way around, and the closure blends into the design.
Can this necklace be customized?
Yes. Length, metal color and karat, diamond size, and total carat weight can all be tailored. Every piece is made to order by American Pearl and Diamond.
Is 17 inches a good length?
Seventeen inches is a flattering in-between length — a touch longer than a 16-inch choker, sitting just below the collarbone so it layers easily and frames most necklines.
This lab-grown diamond tennis necklace was hand-made to order by American Pearl and Diamond. To commission your own or explore more fine diamond jewelry, visit the Royal Collection.