Small Vault. Honest stones.
Harlow Mercantile is a little online boutique. We keep the Vault small on purpose, so every stone in it has been picked by hand, looked over in person, and shown the way it actually is. Every diamond ships with its IGI grading report.
Seven steps, one stone.
- 01
Grown, not mined
Every Harlow diamond starts as a tiny seed in a controlled chamber. A few weeks later, it's a rough crystal that's chemically and optically the same as a mined diamond, just with a clearer story behind it.
- 02
The rough is studied
Before any cutting happens, the rough gets scanned and mapped. Cutters plan the shape that suits the crystal, weighing carat weight against the brilliance the finished stone can actually hold.
- 03
Cut for light, not weight
Cutters work the rough by hand, chasing the proportions that give back the most light. We'd rather lose a few points of carat than hold onto weight that dulls the finished stone.
- 04
Polished by hand
Every facet is polished one at a time, until the surface reads clean under a loupe. It's slow, patient work. It's also the difference between a stone that looks fine and one that looks alive.
- 05
IGI certified
Every diamond goes to the International Gemological Institute for independent grading. You get the full report: cut, colour, clarity, carat, measurements, and confirmation that it's laboratory grown.
- 06
Reviewed by Harlow
Only a handful of stones make it into the Vault. The paper report is a starting point. We look at each diamond in person, in ordinary daylight, and ask if it has the brightness and character we'd want on our own hand.
- 07
Ready for its setting
The stone gets a Vault number, its own photos, and its IGI report. Then it waits for the person who'll design its setting, whether that's with their own jeweller or with us down the road.
What earns a spot in the Vault.
A grading report is a starting point, not the whole story. Before a stone gets listed, we pick it up, turn it in the light, and ask one simple question. Would we be proud to give this to someone we love?
Cut first
Cut is the single biggest thing that decides how a diamond actually looks. A well-cut stone at a modest colour grade will out-sparkle a poorly-cut one on paper every time. So we start there.
Eye clean at arm's length
We don't chase flawless grades. We want stones that look clean at arm's length, so your money goes into brilliance instead of a line on a certificate.
Colour that flatters skin
For colourless diamonds we usually stay in the D to G range. On fancy shapes we'll take a bit more warmth when it makes the stone feel alive instead of icy.
Character over volume
We'd rather list one stone with real presence than ten average ones. The Vault grows slowly on purpose.
A small online boutique with a Vault we know by heart.
Harlow Mercantile is an online boutique for hand-picked lab-grown loose diamonds. No showroom, no wall of a thousand stones. We keep the Vault small because we'd rather show you a few diamonds we really believe in than run a catalogue that feels like a lottery.
Every diamond here is picked one at a time, photographed as it actually is, and listed with its IGI grading report. Nothing is a stock shot or a stand-in. What you see is exactly what shows up at your door.
Got a question? Send us a note. A real person will write back, usually the same day.
What we promise.
Six things we stand by, from the diamond itself to the box it turns up in.
IGI Certified
Every diamond ships with its IGI grading report. Full stop.
Ethically Lab-Grown
Same crystal as a mined stone, just with a clearer story behind it.
Secure Shipping
Insured and tracked, from our bench to your door.
Honest Pricing
Fair prices, plainly listed. No pressure, no upsell.
Real Support
Questions land with a real person. We usually reply the same day.
Signature Packaging
Arrives ready to gift, hold, or hand to your jeweler.
Custom fine jewelry is coming.
Engagement rings, earrings, pendants, and necklaces are on our list. Join the Vault List and we’ll ping you the day they land.
See what made the cut.
The Vault stays small on purpose. Every stone is one of one, picked by hand, shown as it is. Every diamond arrives with its IGI grading report.