Rose Quartz has magical fire like Spike… except her fire is frost (the Crystal Empire view her ice powers as the ultimate sign that she’s a blessing for the kingdom). Rose’s ice breath can freeze objects or if she wants to, it can function like Spike’s fire breath and transport objects or send letters – she can also exhale it onto her claws and then control the magic in much the same way unicorns can.
 
If she’s mad or loses control or succumbs to greed – her frost turns into blue fire and it’s hotter than most dragons flames and her magic is much more powerful but much more uncontrolled, chaotic and sporadic – she can be a danger to herself and others.