The coin is worth about £150 alone, as for the ring mount depends on the carot, could be worth about £200 or more combined
A British 1908 22 carat gold Half-Sovereign (Edward VII)(minted in London - no mintmark), uncirculated and in absolute mint condition could fetch up to £95 GBP. If it has been circulated but still in good condition, it might fetch anything from bullion value to £70 GBP. A British 1908 22 carat gold Half-Sovereign (Edward VII)(minted in Melbourne - mintmark = M), uncirculated and in absolute mint condition could fetch up to £750 GBP. If it has been circulated but still in good condition, it might fetch anything from bullion value to £115 GBP. A British 1908 22 carat gold Half-Sovereign (Edward VII)(minted in Perth - mintmark = P), uncirculated and in absolute mint condition could fetch up to £4,250 GBP. If it has been circulated but still in good condition, it might fetch anything from £80 to £1,300 GBP. A British 1908 22 carat gold Half-Sovereign (Edward VII)(minted in Sydney - mintmark = S), uncirculated and in absolute mint condition could fetch up to £475 GBP. If it has been circulated but still in good condition, it might fetch anything from bullion value to £85 GBP. The values quoted are the best possible for the best specimens in their grades, but may be significantly lower due to varying demand for the coin and the prevailing economic climate. A reputable coin dealer will be able to give a more accurate valuation based on inspection of the coin.
Around 500:)
You are going to have to be a lot more specific. You need to tell us the denomination of the coin and condition if you want to know the value. All you've told us is you have a British coin from 1908 with Edward VII on it.
Edward Cakobau was born in 1908.
Edward Bartlett died in 1908.
Edward Lowinsky was born in 1908.
Edward Kobyliński was born in 1908.
Edward Whitehead was born in 1908.
Edward Monson died in 1908.
Edward Malet died in 1908.
Edward Smouha was born in 1908.
Edward Stutterheim was born in 1908.