Hi, thank you for your question.
Having looked into this for you, I can confirm that 375 will be a hallmark on a piece of jewellery to identify its purity of gold. In this case I can advise that when you see this marking it will be 9ct gold with a 37.5% gold content.
Thank you for using Argos Q&A.
Charmaine @ Argos
Location: Acton Gate
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