At Mari Thomas we strive to do better and want to create better business practices to support positive action towards caring for both people and planet.

We believe that little differences within small businesses, such as ourselves, will make for big environmental change across the World. More so, given the rapid globalisation of the jewellery market and the use of stones and metals mined from every corner of the Earth.

Therefore, at Mari Thomas we are committed to being as responsible from the way we hand make our jewellery in our in-house workshop, to the precious metals and stones
 we source.


As a small team, we consciously try and manage or develop ways in which we can tread lightly on our planet and reduce our environmental footprint. Before “sustainable” became the hot topic in the fashion and jewellery world, Mari had always crafted jewellery pieces with recycled precious metals, from gold, silver to platinum. We prefer to use gold and silver metal that is recycled over mined and fair-mined to ensure we are gentle on our planet, preventing environmental pollution and damage.  

Due to a new health warning flagged by our casting companies, recycling old platinum in a cast project exposes a health risk at high temperature, as unknown alloys contain metals that are toxic when released at high temperatures and enclosed spaces. Platinum is now sourced from new, from sources they know are safe. (If you have any platinum jewellery that you would like remodelled, please get in touch, there are still options available).  

Inside the workshop, the engineering side of jewellery, we collect and gather fine dust and all old scrap metal to reuse in our jewellery collections. Nothing is or was ever wasted!


We only use conflict-free and ethically sourced natural diamonds and gemstones, as well as offering lab-grown diamonds as an alternative, sustainable option.

We have always worked very closely with our stone dealers to ensure that our mined stones have all been sourced following fair labour practices and sustainable agreements. This measures the effect on people, communities, and our social
footprint. Helping to ensure fair play, safe working conditions, environmentally sound practices, and that no human rights have been abused.

We have always and will always work only with ethically sourced diamonds and gemstones, and will not handle any stone if its provenance is unknown or in question.


We are based in the beautiful old market town of Llandeilo West Wales. “Cosy, beautiful and untouched”, Llandeilo has been chosen by the Sunday Times as the top place to live in Wales and represents the best of the UK. 

Llandeilo a “country chic” town is herald for its individual, independent boutique shops and bustling town festivals that bring people together, promoting community harmony through entertainment and joy, the highlights being the Literature, Jazz, Music and Christmas Festival of Senses. 

Mari Thomas Gallery has been based in Llandeilo for just over 10 years, she has well and truly made her mark by purchasing and restoring a gorgeous three storey grade 2 listed Georgian building that was the Old Castle Hotel. It has transitioned nicely into the home of her gallery and workshop.


Mari Thomas boxes and bags are not made from recycled materials, but they are all recyclable. The trees used to produce the bags and boxes are replanted in production and to complete the cycle they can be recycled. We encourage to reuse and recycle wherever possible.

In house we are always implementing little changes. To limit the amount of plastic used within the gallery and workshop and we store each jewellery item using recyclable and naturally biodegradable glassine bags and our dispatch boxes are made from recycled material and are fully recyclable.

Collectively, the small changes we make together can make a big difference.


With every order you make, you help us plant a tree!

We decided to partner with Ecologi as a way for us to play a role in helping to revive and restore our planet. Through projects supporting tree planting to community restoration each purchase you make on line from Mari Thomas sends a percentage of the sale automatically and directly to these projects.  

Ecologi are aligned with our values and are a fantastic gold standard, B - Corp organisation who are authentic and transparent – with their range of projects supported through their organisation being easily accessible.  


We are a small and dedicated team of jewellers in the workshop producing and working on Mari Thomas designs.

Mari Thomas, Nia, Sara, Sue and Katy are all trained and qualified artisan jewellers and goldsmiths. 

The workshop is nestled inside Mari Thomas Gallery. It is on view and is a big part of the unique experience of visiting the gallery; peek through and you can see the girls at work making by hand Mari Thomas collections, producing new bespoke commissions to restoring or repairing jewellery pieces. 

Occasionally we work with other specialists within the industry like casters and hand engravers, most are based in or around Birmingham's jewellery quarter, where Mari Thomas originally trained. It Is also the location of her hallmark (Birmingham Assay Office), we are proud to say that all the work is made in the UK.