As with all decent questions there’s not a very quick answer to this. All insurance policies are different and it’s important you know what they need from you. Make sure you keep receipts of items you purchase and it”s a very good idea to take photographs of them, alone and being worn. To have an image when something has been lost is a blessing, it makes re-creating the item as close to the original possible, gives a good idea of scale and can help prove you owned it in the first place.
As a guide I would check your jewellery insurance around every 4-5 years, particularly if you are fortunate to have many diamonds or precious stones. It is worth mentioning here that with steep gold prices even plainer pieces can add up. Diamonds are bought and sold internationally in US dollars so any significant changes in the currency rate will also play havoc with current retail prices.
There are many types of jewellery valuations but the most common is Retail Replacement Value, this is assessed as the current price it would be to re-buy or re-make the item if it were to be lost or stolen. This will be judged on the gold price of the day of the valuation, the market value of the stones and the labour cost of the making. Most valuers will charge an hourly or by item price, the trend to charge a percentage of the value of the item is rarely used now. I always try to combine polishing or re-stringing for my clients whilst appraising the items so that there is some benefit to the pieces being away from their owners – although wherever possible a home visit to value is the most sensible thing to do.
Jewellery can so often mean more to us than just money but the ability to re-create a much loved piece after it has been lost cannot be underestimated.