Cartridge new or used ?


How do I know if a cartridge is new or used and number of hours played ? 1- If it is bought from an individual or 2- Could it be that a HiFi store sells used or a "Demo" without anyone knowing it? 3- Is a cartridge that remains on the shelf of the store for 3 or 4 years, retains its same performance or its internal parts, can harden and lose their flexibility of reading? 4- Is it easy with a magnifying glass to see the wear of a cartridge, if so what would be the best magnification to use?
audiosens
chakster,, there is a very big difference between a cartridge that has been well taken of by the original owner and one that has been worn out and possibly damaged by the prior owner. Obviously, as a cartridge is used, it wears, IOW..it is a wear item. The question is how it was treated in its past, not that it is wearing as we play it.IMO
I have some questions for all of those folks who buy used vintage cartridges, or used non replaceable stylus cartridges...
how do you know the condition of the diamond? Do you look online and get a generic picture that may or may not correspond with the stylus shape you are expecting to see, and are you able to actually view all of the facets of the diamond..on all sides, or are you doing something else? Using a high powered microscope? Are you able to determine the exact cut and angular correctness of the facets? 
Some other method to determine wear and condition? Do you have any idea as to the condition of the suspension and what that is supposed to perform like...or do you not care about this aspect that much, and assume all is as it was from the factory originally?

@chakster 

I don’t know who was responsible for the 80’s AT cartridges, but maybe their customer service department may be able to help. 
Ya pays ya money, ya takes ya chances. Glad to hear others have had good luck with preowned carts.
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