I don't know if the same goes for other countries, but in the UK gold sovereigns and silver and gold britannias are legal tender and as such are NOT subject to capital gains tax.
At least at the moment. I think we all know that as the shit begins to smother the fan governments will rip up and rewrite whatever laws they feel like.
But if you are UK tax resident and thinking of buying some gold or silver coins, you should be aware that under the current state of affairs at least, you are needlessly exposing yourself to taxation if you opt for maples or eagles or krugers rather than the above coins.
There is VAT on purchases of new silver in the UK (but not gold). One way to avoid VAT is to buy old, predecimal silver coins eg on eBay. Up until 1919, British silver coins (threepence, sixpence, shilling, florin, halfcrown, crown) are 92.5% (sterling) silver. From 1920 to 1946, they are 50% silver. For newbs, remember, silver and gold are measured in troy ounces which are a few grams heavier than cooking ounces.
This rough calculator might come in handy in assessing the price to pay for British junk silver: