KOS Jewelry - Lab Grown Diamond แหวนเพชรแท้ 1-30 กะรัต
4 4/1-4/2 Rama I Rd, Pathum Wan, Bangkok 10330
Lead with the certification conversation. Every diamond here is graded by GIA or IGI and laser-inscribed to match its report, which matters when you're comparing lab-grown pricing across Bangkok. The bespoke ring service is the smarter route if you already know the shape and carat you want, and the 30-day money-back guarantee takes some pressure off the decision.
KOS operates as a sub-brand within the CELI Jewelry showroom on CentralWorld's first floor, room G109/1, tucked into the Groove Zone on the Rama 1 entrance side. The counter shares the space with CELI's natural diamond inventory.
The family behind CELI has dealt in natural diamonds and gemstones since 1975, and KOS is their lab-grown division, launched to offer the same gemological rigor at a different price point. Stock runs over 500 certified stones at any given time across twelve different diamond shapes, including the classic round brilliant, oval, emerald, princess, and cushion cuts, plus less common specialty forms like crisscut and asscher. Every diamond carries either GIA or IGI grading and a laser-inscribed serial number that matches its certification document, so you can verify the stone's exact specifications against the official report independently before purchase. Price starts around ฿10,500 for simpler settings and climbs past ฿260,000 for larger carats mounted in 18K gold, with most completed rings landing in the ฿14,000 to ฿100,000 range depending on the diamond's size, clarity grade, and setting complexity.
The shop also runs a bespoke design service where you pick your diamond from inventory and specify the setting, metal tone (18K gold in white, yellow, or a warmer vanilla variant), and band style through in-house craftsmen who handle the build. Consultation goes through a website form or direct contact by phone and messaging apps like WhatsApp or Line. A 30-day money-back guarantee applies to purchases, and the rental program lets you try pieces before committing to ownership.
The CentralWorld location sits inside the CELI showroom, so if you're looking for a standalone KOS storefront you'll miss it. There's a second branch at Central Ladprao's third floor. Book consultation time ahead if you want hands-on comparison across multiple stones.