I don’t have much to add, as this is my first time hearing of a “GY”
Have you searched for and found a Data sheet?
Where did you buy it from? (link)
If it is from your work, you should be able to get some Reader info, but as a start, They should be compatiable with iClass readers.
iClass so it should be HF ( 13.56MHz ) HOWEVER, some iClass also have a LF Chip (Prox), Have you tried shining a brigh torch light from the back and looking for a 2nd Chip and antenna ( Likely circular antenna in the centre of the card )
Do you have a Diagnostic Card? 
You could try this on a reader and that will tell you if it is HF, LF or Both
This will probably give you most of the answers you are looking for