Hatton Garden and Hatton Wall are lined with trade suppliers of metal, findings and tools for the jewellery industry. Exchange Findings(also trading online as Cookson Gold) are my favourite by far. They’re friendly and helpful, even for students and beginners. They sell all forms of silver and gold, from sheet to chain, and also have a scrap metal service to buy unwanted metal(I imagine you get a better deal that cashforgold…) They also do stones and sundries such as boxes. Top tip: the queues can be very long — it’s best to order online the day before and then come in and collect in person, it’s free and your order is waiting. You can also browse their catalogue online so you know what they have so you’re ready to order when you do get to the counter — they’re patient but also very busy so will try to get you through quickly and get on to the next customer!