There is a common misconception that buying jewelry outside the EU, for example in Dubai, is always cheaper. Unfortunately, this is almost never the case once the actual regulations are taken into account.
As a private traveller, you may only bring goods worth up to EUR 500 into the EU without paying customs duties or taxes. If the value of the jewelry exceeds this limit, you are legally required to declare it at the border and pay both customs duty and VAT.
If you choose not to declare jewelry that exceeds this value, it is considered smuggling, which may lead to fines and confiscation.
In practice, this means it is almost never cheaper than purchasing jewelry directly within the EU — where you also receive full guarantees, insurance options, and a secure shopping experience.