Market · Holborn
Promise Diamonds
Some booking links are affiliate links. If you book through them, we may earn a small commission at no extra cost to you. We never let this influence which places we recommend.
Promise Diamonds is a boutique jewelry showroom located on the second floor of Assay House on Greville Street in Holborn, London. Specializing in ethically sourced diamonds and custom engagement rings, the store offers a personalized experience away from the high-street chains. Upon arrival, visitors are greeted by a consultant who guides them through the selection of loose diamonds and settings, explaining the 4Cs and the origin of each stone. The showroom itself is intimate and modern, with viewing tables and magnifying tools for close inspection. What sets Promise Diamonds apart is its focus on transparency and craftsmanship, allowing clients to see the actual diamonds before purchase and even design their own ring. The Holborn location is convenient for those working in the City or visiting the British Museum.
Don't miss
- View a curated selection of loose diamonds with full certification
- Design a custom engagement ring with expert guidance
- Learn about diamond grading and ethical sourcing
- Compare settings and metals in a private consultation
- Visit the nearby Hatton Garden jewellery district for comparison
Tickets & tours
Ways to visit Promise Diamonds
You don't need a tour to visit — entry is free. A tour is worth it if you want transport, a guide, or to combine Promise Diamonds with nearby sights in one day. That's what these do well.
Cheapest way inDrinks & Diamonds Shopping Experience in St. Thomas5★ · 12 travelers~1 hourFree cancellationFrom$10 per personSee dates →
Best full dayTower of London and Crown Jewels Exhibition Day Ticket4.4★ · 7,254 travelers~24 hoursFree cancellationFrom$51 per personSee dates →
Private & flexibleDiamonds and Cocktails a Shopping Experience in Grand Cayman5★ · 17 travelers~1 hourFree cancellationFrom$10 per personSee dates →Good for
How travelers rate it
Know before you go
- Book an appointment online to ensure a consultant is available.
- Bring inspiration photos or sketches if you have a design in mind.
- Ask to see diamonds under a loupe or microscope to inspect clarity.
- Request a certificate for any diamond you purchase.
A bit of history
Promise Diamonds was founded in the early 2010s by a team of gemologists with a mission to provide conflict-free diamonds and bespoke jewellery at fair prices. The company operates from the historic Assay House, a building associated with precious metal testing.
Common questions
Do I need an appointment?
Walk-ins are welcome, but appointments guarantee personalized service.
Are the diamonds conflict-free?
Yes, all diamonds are ethically sourced and come with certification.
Can I design a ring from scratch?
Yes, they offer full bespoke design services.
Do they sell other gemstones?
Primarily diamonds, but they can source other stones upon request.
Is there parking nearby?
Street parking is limited; public transport is recommended.
What is the price range?
Prices vary widely depending on the diamond and setting; they cater to different budgets.
More attractions in London
