1 kilogram Calorie is the amount of energy needed to raise the temperature of one kilogram of water by 1 degree. 1 gram calorie is the amount of energy needed to raise the temperature of 1 gram of water by 1 degree.

I see there's some use of it after having done some searches, so I'll concede it makes some minor sense as a means to disambiguate due to the Calorie/calorie confusion. Especially as "calorie" and "gram calorie" then means the same thing. This is actually the first time I can recall having seen anyone use it, though, and so for me at least it confused matters rather than clear it up...