Tanzanite Hallmarks....

Updated: Jul 26

It has been full on with bespoke jewellery enquiries and making items of jewellery for clients since my last blog to you all. Two particular Tanzanite jewellery pieces (pictures at the bottom of this blog) we have made are currently at The Birmingham Assay Office for hallmarking with our Maker's Mark, before moving on to AnchorCert for certifying and grading of the Tanzanite gemstones.

Why do we send our jewellery to The Birmingham Assay Office?


Precious metals used in jewellery manufacture are always used as an alloy. The precious metal must be mixed with other elements to give it the necessary properties such as flexibility to produce a desirable and durable article.


The Assay Office explain it well. "When jewellery and silverware are manufactured, precious metals are not used in their pure form, as they are too soft. Gold, Silver, Platinum and Palladium are always alloyed with copper or other metals to create an alloy that is more suitable to the requirements of the jeweller. Such an alloy needs to be strong, workable, yet still attractive. Owing to the high value of Gold, Platinum, Palladium and silver, there are significant profits to be gained by reducing the precious metal content of an alloy at the manufacturing stage. Even the most experienced jeweller cannot tell how much precious metal there is in an alloy, just by looking at it, nor whether a thick plating of gold is covering a base metal interior, such as copper or brass. There is a huge opportunity for fraud and there has therefore always been a need to protect the public, and honest suppliers, from those who are tempted to cheat them."


Therefore all items being sold as gold, silver, platinum or palladium in the UK must be hallmarked to confirm that they meet the legal standard. This cannot be done by the manufacturer or importer; goods must be submitted to one of the four UK Assay Offices, or an Assay Office belonging to the International Convention.

The only items which are exempt are those which are under the legal weight threshold:

  •  0.5 grams for Platinum

  • 1 gram for Gold

  • 1 gram for Palladium

  • 7.78 grams for Silver

So once the item has been hallmarked donating what the metal is, Sterling Silver, Gold, Platinum, Palladium, the next mark to be struck is the Maker's Mark.

When we started making jewellery some years back now, we applied to The Birmingham Assay Office for our own Maker's Mark.


We were so excited when we went to visit the Assay Office and actually hold our very own Makers Mark that has the tiniest little logo "TJ". It's kept in the same filing system as all the other jewellers in the UK (some incredibly famous names too!) so we are there with the best of them.


Once the Maker's Mark has been stamped on the ring, the final compulsory stamp is the logo for the Assay Office that has hallmarked the item. For Birmingham, land locked Birmingham, they have the anchor!

The hallmark of the Birmingham Assay Office is the Anchor, and that of the Sheffield Assay Office was the Crown. ... It is said that the choice of symbol was made on the toss of a coin which resulted in Birmingham adopting the Anchor and Sheffield the Crown (which was changed in 1977 to the White Rose of York).


Whether this story is true or not, I have no idea!


So having gone through all these checks, both me as the jeweller, and you as the customer have peace of mind, and these two customers of ours know that what they ordered from us is exactly what they will receive. Now THAT is really important to us.


Next week I shall update you on the certifying of a Tanzanite gemstone and let you know what grade these beautiful pieces came back as. What do you think?



If you are interested in custom made jewellery simply contact us to learn more.



01531 631557

27 The Homend, Ledbury HR8 1BN, UK

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