Best bet is to have your friend look at her curling iron and see if it has a switch for voltage. The switch will usually just have two numbers on it - something like 110/115/120 and 220/230/240. If so, all she needs is a plug adapter. Turn the switch to 220/230/240 when you're in a 230v country.

The converter you link to should be fine for any curling iron/hair dryer/whatever if put on the High setting.