Gary,
finally something i reckon i know the most about --
We manufacture gloves internationally and it really depends where the gloves are made and who is the owner of the company i.e. eurpean/asian/african etc
Eurpoean hands are larger than Asian, African hands have a wider distance difference between thumb and forefinger.
Most gloves are made in Sri-lanka/Malaysia/China etc but their owners sit in Europe.
some of the better brands will give you a sizing chart for their range of gloves, but one chart is not generic unfortunately.
we have industrial gloves used on the mines in the bowen - they are absolutely terrific for fishing (not selling give me a minute)
beating the abrasion resistance of leather by more than 8 times the resistance.
i always have stacks of them on my boat for the boys - me however i am a brand man junkie!!!! so even though the gloves are great and are in most aspects probably better ( no slipping after you pick up a wet GT).....i just can't handle the industrial Safety STD marking on the glove in pictures and I'm tired of photo shopping them out!!
so i have used most and to sum up......
industrial Nitrile/PE gloves (nik them from stores
but make sure they are mine
) are the cheapest safest throw away able option
most of us have used Cultiva brand - they to me are okay pity about the inside seam and bulky finger and slimy grip after handling a GT.......but if you have worn them then this is where you get your sizing from......
so Cultiva are a more generic European sizing - so if you are looking to order online for fishermen or my new favourite (Shimano Ocea) gloves from online stores then general rule of thumb is to go one size bigger and you SHOULD be good - i say should so don't come chase me if they are not ----
hope that long winded nonsense helped my man!