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The Cosima

Past, present, and forever — in a single setting.

From $650 · Made to order from Brooklyn

↓ Explore The Cosima
The Cosima engagement ring setting

Make It Yours

Setting Type

Setting only — accent diamonds are not included. Your chosen center stone will be professionally set before shipping.

Metal
Stone Shape
Center Stone Size

Center stone seat size — match your diamond to this measurement. How to measure your ring size →

The Cosima: from $650

✓ Free returns within 60 days ✓ Free shipping ✓ Lifetime warranty

Set by hand in NYC · 60-day free returns

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Design Your Cosima

Your setting will be pre-filled in the ring builder — choose your center stone next.

Not sure? Speak with us — we’re happy to help.

The Story of The Cosima

The Cosima is a three-stone engagement ring crafted in 14K yellow gold featuring a square 5.00x5.00mm lab-grown diamond center stone. Handmade in our woman-owned Williamsburg, Brooklyn studio, this ring combines classic design with modern ethical standards.

This design showcases a semi-set setting style with secure prongs holding the square center diamond, accompanied by round accent stones totaling 0.75 carats. The shank has a smooth profile, highlighting expert craftsmanship that balances elegance with durability, making the Cosima ring distinctive in its refined yet bold silhouette.

We use 100% recycled solid gold that is never plated or vermeil, paired with conflict-free, ethically sourced lab-grown diamonds. Each diamond is IGI and GIA certified ready, reflecting our commitment to transparent, responsible jewelry-making from our Brooklyn studio.

The Cosima ring is available in standard sizes, with the semi-set style allowing the center stone to be prominently displayed while securely framed by the accent stones. Custom sizing and configurations are available upon request to ensure the best fit and style.

Every piece is made to order. Once your order is placed, we'll send you a confirmation email with your estimated completion date. Most orders ship within 2 to 3 weeks, and we will notify you immediately when yours is on its way.

  • Metal: 14K recycled yellow gold
  • Stone shape: Square center diamond with round accent stones
  • Center stone size: 5.00x5.00mm
  • Accent stones: 0.75 CTW, G-H color
  • Setting type: Semi-set

Specifications

DimensionOptions
Metal Options10K Rose Gold, 10K White Gold, 10K Yellow Gold, 14K Rose Gold, 14K White Gold, 14K Yellow Gold, 14K X1 White Gold, 18K Palladium White Gold, 18K Rose Gold, 18K White Gold, 18K Yellow Gold, Platinum, 14KPW
Stone ShapesAsscher, Cushion, Emerald, Marquise, Oval, Round, Square
Setting TypesSetting Only · Complete Setting
Side DiamondsNot included with Setting Only
Price Range$650 – $1,600
Materials100% recycled gold · IGI/GIA/GCLA-certified lab-grown diamonds
StudioWilliamsburg, Brooklyn
WarrantyLifetime craftsmanship warranty

Recycled Gold

Every setting cast from 100% reclaimed precious metal — conflict-free, always.

IGI-Certified

Every stone carries a full IGI certificate. No exceptions.

Made to Order

Every piece produced to order from Brooklyn. Woman-owned, independently operated.

Lifetime Warranty

We stand behind every piece we make — for life.

Frequently Asked Questions

All of our diamonds are 100% lab-grown. They are chemically, physically, and optically identical to mined diamonds — but more sustainable and conflict-free. Learn more about our sourcing →
Yes! Our Williamsburg, Brooklyn studio welcomes walk-ins during open hours. You can also book a private appointment for a dedicated one-on-one experience. Try on styles, explore customization options, and meet with Sue in person. Visit or book an appointment →
At Haejin Jewelry we proudly stand behind every piece with our Lifetime Warranty, covering manufacturing defects, prong tightening, and complimentary cleanings. We also offer returns and exchanges within 60 days of purchase (custom designs may vary). Returns are free with our prepaid shipping label, and in-store purchases can be returned at our Williamsburg studio. Read our full Refund Policy and Warranty →
Lab-grown diamonds are more affordable and sustainable than natural diamonds. They offer the same brilliance and durability, but without the environmental or ethical costs. Learn more about the economics of lab-grown vs natural diamonds →
Yes, we ship worldwide. All orders are carefully packaged and fully insured for transit. Domestic orders within the United States typically arrive within 7 to 14 business days. International shipping times vary by destination, generally 15 to 27 business days. Customs duties and import taxes may apply depending on your country and are the responsibility of the recipient. Contact us before ordering if you have questions about shipping to your location.
Yes — every ring we make uses 100% recycled solid gold. Recycled gold is chemically and physically identical to newly mined gold, but its production avoids the environmental destruction and human rights concerns associated with gold mining. Choosing recycled gold is one of the most meaningful steps you can take toward an ethical engagement ring. It is a commitment we make on every piece, not an optional upgrade.
Yes. Haejin Jewelry is a woman-owned independent business founded and operated in Brooklyn, New York. We curate every piece and inspect every ring before it ships to you. As a small independent jeweler, we pour genuine care into every order — from the sourcing of our recycled gold to the final quality check. When you buy from Haejin Jewelry you are supporting a local Brooklyn business, not a corporate chain.
The number refers to gold purity. 14K gold is 58.3% pure gold mixed with other metals for strength and durability — it is harder, more scratch-resistant, and more affordable. 18K gold is 75% pure gold, giving it a slightly richer, deeper color and a softer feel, but it is more expensive and slightly more prone to scratching over time. For everyday wear engagement rings, 14K is often the practical choice. For those who prioritize the highest gold content and richest color, 18K is worth the premium. Both are available in white, yellow, and rose gold at Haejin Jewelry.
An unset ring setting — also called a mounting — is the metal portion of the ring without a center stone. It holds the diamond or gemstone but is sold separately so you can choose exactly the stone you want. At Haejin Jewelry, our ring settings are designed to be paired with a lab-grown diamond or gemstone of your choice through our online ring builder. This gives you full control over the size, shape, and quality of your center stone.
Most of our settings are designed for a specific center stone shape and size range. Our online ring builder automatically shows you compatible lab-grown diamonds for each setting — so you’ll only see stones that will fit perfectly. If you have a specific stone in mind, our team is happy to help you find the right setting match. Contact us or visit our Williamsburg Brooklyn studio for personalized guidance.
Most custom engagement rings are completed within 3 to 4 weeks from the time your order is placed. Rush options may be available depending on the setting and stone selected — contact us to discuss your timeline. Each ring is made to order by skilled artisans and carefully inspected before shipping. We recommend ordering at least 6 weeks before your target date to allow time for sizing adjustments if needed.
Our ring settings are available in sizes 4 through 12, including quarter sizes such as 4.25, 4.5, 4.75, and so on. Half and quarter sizes are available on most styles. If you are between sizes or unsure of your size, we recommend our free ring sizing guide or visiting our Williamsburg Brooklyn studio for an in-person fitting. We can also advise on sizing adjustments after your ring is complete.
Our engagement ring settings are available in 10K, 14K, and 18K gold in white, yellow, and rose, as well as platinum and two-tone combinations. 14K white gold is our most popular choice — it offers excellent durability, a bright white finish, and a lower price point than platinum. 18K gold has a richer color and higher gold content. Platinum is the most durable and hypoallergenic option, ideal for those with metal sensitivities. All metals are 100% recycled solid gold or platinum — never plated.
Yes. Most ring styles can be resized one to two sizes up or down after delivery. Some designs — including eternity bands and rings with stones set all the way around — cannot be resized without affecting the stone setting, so we strongly recommend confirming your size before ordering those styles. If you need a resize, contact us within 60 days of receiving your ring and we will advise on the best approach. We also offer complimentary first-time resizing on select styles — ask us when you order.
Each ring setting is designed for a specific center stone shape and size range. Our online ring builder automatically filters compatible lab-grown diamonds and gemstones for whichever setting you select — so you only see stones that will fit perfectly. Common shapes include round, oval, cushion, emerald, pear, marquise, heart, and radiant. The compatible shape is listed on every setting’s product page under Specifications. If you have a stone already and want to find the right setting for it, contact us and we will help you find the perfect match.