Below is what we understand of the laws in the UK.
We always urge customers to get legal advice.

 
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This information below applies to RE sellers and not private customers.

As a private customer or giving as a gift you can do whatever you like.  EG attach 10 charms with different trademarks and give them to a friend.

It has been bought to our attention that some customers are purchasing items that have trademarks and or copyright marks and are then putting these items onto existing jewellery and Reselling as a complete piece.

Please be aware that this, as far as we are aware, breaks the law.

Examples
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Example A

A charm has a trademark called SupplierA
A bracelet has a trademark called SupplierB

You attach the charm with trademark SupplierA to a bracelet trademark SupplierB.
You created a piece with 2 trademarks and by law this creates public confusion.
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Example B
A charm has a trademark called SupplierA
A Bracelet has NO trademark.

You attach the charm with trademark SupplierA to a bracelet without a trademark.
You created a piece with 1 trademark and by law this creates public confusion due to the fact that it would be believed that the trademark SupplierA made the entire piece.
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Example C
A charm has a trademark called SupplierA
A bracelet has a trademark called SupplierB

You have the items listed separately on your website.
A PRIVATE customer of yours buys them separately and asks you to fit together.
This is fine and legal.

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You may think " Who cares as long as you get your money".
That would be nice but as with any LAWS, we must follow them.
Below are some links to various websites that probably confuse more than help but when you look closely and think about it all, it does make sense.

There would probably be only one in a million cases where creating a derived piece would cause a problem but it has happened with very serious legal consequences. (not to us thank goodness)

It is with regret that if it is bought to our attention that a trade customer is making a derived piece then we will have to stop accepting orders from them.

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