Whats The Gold Grade 24k? Of Most Nuggets Found These Days Around Globe?

[DDancer]

The only way to know the true purity of ones gold that I know of is with an assay.  Granted your destroying nuggets in assay so its a personal call when grading raw gold when you go to sell or buy them. 
XRF devices only scan a very shallow specimen, few microns deep, for the spectroscopic sample that they read however its very accurate and indicative of the overall mixture of the gold.  Scratch testing, though invasive, is also a shallow test and the regents used have a wide margin of error.  Specific gravity tests have a wide margin of tolerance as well making them pretty much impossible to calculate all the materials in the specimen being measured for purity.

That being said knowledge of the geography of where a particular nugget was found helps with grading the purity.  Here in America and in Australia, as well as other parts of the world, local knowledge combined with testing are ones best bet for a reasonable grading of raw gold.  For myself experience over the years usually leads me to talk to the locals about relative grade of raw gold for any area that I've visited.  They, the locals, have general knowledge as there is always one or more of them who have assayed their gold at one time or another~ so I don't have to destroy my nuggets to feel good about their grade myself.

My thoughts.

[idahogold]

All great responses! Thanks for the Info!