Iran Gold Coin

Even at the best of times I'm barely literate in the Arabic script and its derivatives, but your coin looks like a half pahlavi from the inscription on it.
http://en.numista.com/catalogue/pieces64359.html

I don't think your coin is authentic. I think I can see plating bubbles everywhere on the surfaces, combined with an off-center strike, bold/smooth lettering and mushy details on the lion.
How much does it weigh? 4 grams should be correct if it's gold.
Try checking if your coin is magnetic with a magnet.

You can probably see what I mean if you compare your coin to these numista pictures, showing the authentic coin.

I don't have the scale, so can't tell you the weight, but I will test is it magnetic.
Yeah, I see what you mean, but can't see any difference when I loupe it..then again, I'm no expert at this :)

To be fair, I'm nothing more than an enthusiast who happened to take an interest in all sorts of modern world coins and investigating fakes, but I am by no means a professional.

If you want to be sure your coin is gold, you could always walk down to a jewlery/coin/pawn/"WE BUY GOLD" shop to get them to weigh it/test it somehow. Heads up, they might want to charge you when testing with chemicals. They might scratch the edge of your coin to remove a trail of its conposition to see if it reacts with acids. Gold is very non-reactive.

Scratching a coin like this can possibly remove any plating to reveal what's under it. As for this coin, it should be solid a solid alloy of 90% gold, silver and copper. Scratching leaves ugly markings though, which is very undesirable to collectors who would pay much for high-quality pieces (such as yours if it turns out to be authentic, so hande it with care!)
The risk is that this is a modern Chinese fake, if you check out some topics here on CCF then you'll find out that this is a common practice, to counterfeit older coins simply to fool collectors or make some quick money.

Lastly, and even though this is extremely relative and non-conclusive, does the coin feel heavy for its size? This can give you a hint or a feeling. Gold is a dense metal and in volume weighs significally more than most other metals found in coins.
Compared to say a US dime (or any coin with same diameter), is it heavier or lighter?

If it's sentimental, then it doesn't matter much if it's authentic or not, it still holds memories.

I'm not entirely sure about the collector's value for these, but considering they pop up from time to time, they seem decently common so I'm gonna guess it's worth close to its melt value in gold, which would be about US$130, with actual prices increasing with condition. Much for just a little coin the size of a dime.

Again, weighing coins that way IS very relative, a professional scale would be the best for sure. No need to harm a sentimental piece.