Real Or Fake?

If any of those tested 24k they are fake. None of those coin were made of pure gold, all were alloyed with copper.

Coin 3 should be 2.5mm larger than a Washington quarter. Coin 2 should be notably larger than a Lincoln Cent. 21.6mm for the G$5.00 vs. 19mm for the Lincoln. Lastly the G$50 should be 2.1mm larger than a Kennedy half.

That said none of the coins appear fake. Weight and dimensions will confirm common dates are primarily gold.

Assuming you're talking about XRF analysis, the accuracy should easily be enough to confirm that these aren't real, because all of them are alloyed ~10% and shouldn't be over 22kt. If the analysis is less-accurate than that, then it's not certain.

Coin 1: Should be 0.1mm larger than a Dime, and your weight is about accurate to the extent that a scale with 0.1g resolution can be accurate.

Coin 2: Should be significantly larger than a Lincoln Cent; it's almost 1/8" larger in real life. Weight is OK.

Coin 3: Again, it should be almost 1/8" larger than the Quarter referenced. Weight is OK.

Coin 4: Diameter is OK if you meant 1mm all around, because it should be 1.7mm larger than a Kennedy. Weight is OK.

I can't say I'm optimistic about any of them. If they're real, you can assume none of their values to exceed melt by much.

It is also possible that the electronic devise you used was inaccurate. I'm not an expert, but I think it is less likely that a fake would be made with 24k gold instead of ~22k gold.