Is this a good idea or not, and can you give your advice?

I'm thinking of buying something fairly valuable (say 拢250 max) that's likely to go up in price as a little investment and a bit of fun.

What's best for this? A diamond? ruby? Penny black postage stamp?

I think an investment grade diamond or ruby might set you back a tad more than 250. A penny back somewhat less than 250.

You might give a little consideration to an ancient greek coin. Some can be had in that price range. One that is very popular and priced at about that range is the tetradrachm of Mysia, Pergamum. It is a large coin, one of the largest minted for common usage during that period, silver. Minted about 100 bc. A nice xf-au coin should run about 250. There are also quite a few others you could choose from. A drachm from Istrus is smaller but has a very interesting design and very well executed. Minted in the 4th century bc. You may be able to obtain an almost mint coin for about 250.

Just think about it. A coin minted over 2000 years ago. In the case of Isrus about 2500 years ago.

I would not do it unless you have a field where you are an expert at and know exactly what you are doing.

It is a bad idea for sure. invest in your knowledge

I don't want to seem harsh but do you know what you are doing?
拢250 fairly valuable ! What sort of diamond, ruby or penny black are you going to get for that ? Buying something you don't know anything about is an almost certain recipe for disaster. Stick to something you do know about. If you can't think of anything do a bit of research (you've got a computer & Google so there's where you start).

I don't know anything about the market for British stamps but last I heard the high-end US stamps of the classic period were red hot and everything else was pretty stagnant. I don't know if you can get into the high end for 250 pounds, but if you're knowledgeable about stamps you can find out. With any tangibles you've got to control your buying and selling costs; dealers make 99.999999% of the money in collectibles. Depending on where you're buying and selling, the collapse of the dollar may be a concern as well.

I don't know about the UK, but I think the US is in danger of major inflation, and if that comes to pass gems will do well (in dollar terms), and stamps have a lesser chance of catching investor interest. In general, however, the stock market will trounce tangibles over the long haul, so you ought to put this in your entertainment budget rather than your investment budget.

None of those!

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