Opinions On Method I Use To Help Check Authenticity On Pre 33 Gold.

Die comparison studies are the best way of detecting fakes that are of correct weight and alloy. Recycled .900 coin gold and silver is occasionally used.
Copies off a genuine coin generally have slightly fuzzier design detail

It is of great help to understand the various techniques on how very high quality fake and counterfeit coins are made.
A good book reference:
'Numismatic Forgery', copyright 2004, by Charles M Larson
ISBN 0-9742371-2-4
endorsed by none other than Ken Bressett, Past President ANA.

Deceiving fakes are best detected by their method of manufacture, by close examination, hand held, with at least a 10X loupe. That is one reason why I am not keen on slabbed coins. There are a few fake slabs out there.

It must be remembered that fakes are also made by altering a genuine coin. Sometimes mint marks are added, the first attempt at detecting this sort of fake is to give the suspect coin a long acetone soak, the see if the added metal falls off, or is easily removed.
Also, dates are altered, and so careful examination is required, looking for metal disturbance which should not be there.

For my own education, I maintain a growing collection of highly deceiving fakes. I only buy them on the condition that they are sold as counterfeit, fake or copy.

I always hold in high regard those here in the CCF who are happy to put in the 'hard yards' in the detection of minor error and variety coins, - that is the start of a good education in the detection of fake coins.

I have only ever matched two coins with die cracks to images in the PCGS web site. One was the 1897 double eagle I showed here in the past. The other was an 1890 sovereign. That one had perhaps a die flaw not a crack.

I think that the odds of finding two coins with the same die cracks are low. From national mint workers in my country I have heard that the dies for striking gold and silver were expected to be used for 2000 coins before being replaced or reworked. In the nineteenth and early twentieth century, when presses were driven with steam power. Other countries could have had different standards. But this means that many dies were used in large issues. You can see this in sovereign issues that had numbered dies. There are years with more than 100 dies.

To find coins with the same die cracks you will have to find a coin struck with the same dies used in those in online photos. In a year with a million coin issue the odds of finding a coin from the same dies would be less than 1%. Only a small fraction of that 1% would have been struck when the die was already damaged. Damaged dies were supposed to be replaced.

The idea is interesting. But it will not be easy to find matches. Especially for coins of the USA. I think that the mints there had better quality control than the british and others. I have seen fewer american coins with die cracks.

I've found a match! Lol
I've matched my 1904 $20 liberty to one of the hi res pics on the pcgs website, it's the third up from the bottom of the list.
There is die cracks in 3 different areas that match my coin .
I looked at every single pic of the 1904 $20 liberty, (there is a lot of them ! ) And only found one with the same die cracks as my coin.
I've absolutely scrutinized the cracks with magnification too :)

Pretty happy to have found this :)

good topic, thanks for posting this..

The use of die cracks to authenticate gold coins is a good tool, but not full proof. Counterfeit transfer dies pick up the imperfections on the host coin including die cracks. You could include the die cracks with the other tools to evaluate authenticity that would include soft mushy details, repeating depressions, color, weight, tool marks, comparing to genuine example, edge evaluation, date and mint mark location, shared dies, bumps & bubbles, die wear, circulation wear, luster, cleaning to hide imperfections, details off, denticles off, etc.