What ICOT and GAW have said is extremely reasonable (as usual). Gold is normally thought of as an inflation hedge, and it doesn’t make a good “investment”. The same amount of gold that was created at the beginning of time is the amount of gold on earth today – it does not oxidize and it is not manufactured (can be through nuclear means, but that’s not done). The amount of gold available for buying and selling is something pretty hard to change – when the price of gold is high enough, people will sell their jewelry and mining companies will find it worthwhile to dig gold out of the earth at lower gold to ore ratios, but all that has a barely noticeable impact to the supply.
If you are worried about currency devaluation, as many people are when they think about all the money being printed at the Treasury department, then trading your currency for gold can make sense. After all, why let your dollars sit in a bank account and lose their buying power every time the money supply is increased? It is a much better idea to keep your savings in gold which hardly changes in supply. The gold will still be equally precious when you need to turn it into buying power. You might get more dollars or less when you sell it, but it’s a pretty good chance that the buying power hasn’t changed. You might or might not want an ETF for this purpose, as some people will advise only having physical gold serves this purpose.
However, the buying power of gold can change if there is a speculative bubble one way or the other. Some might say that the current price of gold is high because it is overspeculated. Others say that the price is currently low because it is undervalued. Gold definitely gets a lot of attention these days, but there is really no one who knows what the current price or the recent trend means. The price of gold could shoot up tomorrow, or it could crash and burn like it did in the 80s. Either way, speculating is risky. So unless you are taking on this risk as a hedge, or as part of a diversified portfolio, you are essentially gambling.
By the way, diamonds make better semi-conductors than gold, so arguing that gold is useful for that reason only makes sense as long as the price of gold stays lower than these commercial grade diamonds. Gold is a poisonous metal, extremely heavy, and not easy to use as currency except in large amounts. I don’t want to have any (though I own a small amount as part of a diversified portfolio).