In the
Treasure Hunting FAQ in the Fishing and Treasure Hunting Forum, it gives the dig radius effects of your mining skill. I do not recall any changes to this when they added the mining gloves.
I will test it if I get a chance, but you can test as well. Bring a set of +5 Mining Gloves with you. Once you find your spot, halt your digging by moving. Then stand five tiles away and try to dig it up, if successful, take a step back and try 6 tiles. If you cannot dig it up from five tiles away, then there is no benefit from the mining gloves.
Stayin Alive,
BG