First, Spanish home insurance policies distinguish between "continente" and "contenido".

The former is simply the building itself, while the second is the contents of the building.

Here, the "capital" is the "capital asegurado", i.e. what the item is valued at, which in English is the "sum insured"

"What is the sum insured?
With a sum-insured policy, to arrive at the total amount you should be insured for add together the total of your high-risk items and the total for the rest of your belongings (after making a deduction for normal wear and tear for clothes and linen, as above) and round this figure up to the nearest thousand pounds.

You must insure all your contents for the right amount – if the total sum is too low, whatever amount the insurer pays out will be scaled down proportionately as clawback for under insurance!!"

Apparently, this policy automatically covers 10% of the value of any jewels lost or stolen. i.e. you don't need to make any special provision for this type of loss.

Andy