Default Charger rating

I lost the charger that came with the phone so got myself another charger. This new charger takes a hell of a long time to charge the phone, takes around 3-4 hours to get a full charge. I see that the Current rating is a pathetic 0.7A.

Could anyone let me know what is the Ampere rating of the charger that came with the phone? I'm thinking of buying a 2A charger for quick charging, anyone using such a charger and will that be safe? Thanks in advance for the answers!