Need Help With Gold Dutch Coins Potential Value 2 1/2 Gulden

I would assume it's a "gold miniature", an unofficial copy, in gold, of a Dutch silver coin, made for jewellery purposes.

It's actually called a rijksdaalder, the 2.5 gulden coin. And it reads 'Munt van het Koningrijk der Nederlanden' or coin of the kingdom of the Netherlands (in old spelling).

You're right about not finding anything about these rijksdaalders. There have never been golden rijksdaalders for circulation. All have been silver and later copper-nickel, whereby both silver content, size and weight were reduced over time. The 1937 version should be .720 silver, 25 gram total weight, 38 mm in diameter and have a smooth edge with inscription.

10 gulden coins were indeed made of gold and can be more or less seen as either investment coin or international trade money (at least, it was introduced as such in the past). It actually represents a trade token (standard), while also half tokens (5 gulden) and double tokens (20 gulden) exist, but those two are scarce.

What you have here is thus a token or medal. I do know that a lot of these kind of tokens have been struck by private companies. It should somewhere on the coin read that it isn't legal tender if it's indeed intended as a coin replica. I can't say for sure that it's 24 carat gold, as there are also a lot of those fantasy tokens made to use as, for example, buttons or pendants. You should have it checked at your coin shop or jeweler.

I hope this helps.