Declare at customs gems bought on holiday in Sri Lanka?

Question

If I buy a sapphire for an engagement ring during on a holiday in Sri Lanka will I have to declare it in the airport at customs (both leaving Sri Lanka and returning to the UK)? Will I have to pay fees?

I have been told so but it doesn't seem like that reading around on guides.

For instance I didn't find useful information on the Ministry of Finance Sri Lanka Customs Department. There they simply say:

Gem stones purchased in Sri Lanka can be exported either by Air freight or hand carried by the owner."

Also this German embassy page states:

Sri Lanka's most celebrated export Blue Sapphires, Cats Eyes, Rubies, Star Rubies, Star Sapphires, Alexandrites, Moonstones, Zircons, Garnets, Amethysts, Topaz, etc. are offered for sale at the Sri Lanka Gem & Jewellery Exchange, 310 Galle Road, Colombo 3. A free gem testing service is provided to tourists.

and

the Gem Board offices in Colombo and Ratnapura can provide free taxation and official certificate.

Answer 1

I have seen no indication of any export taxes for tourists taking individual gems out of Sri Lanka. In looking for information, I found on TripAdvisor advice to only buy from a shop that will take the gem with you to the Gem Trading Board for valuation. That seems good advice, and you could ask about the taxation comment when you are there. It may be as benign as a VAT refund on export.

The value of the sapphire will matter for importing it into the UK. The duty free allowance for "other goods" from outside the EU is currently 390 pounds. See Bringing goods into the UK for more information. If you are exceeding any of the duty-free limits you need to take the red channel on leaving baggage claim and have information about the values etc. ready.