It sounds like you are describing Rarity one of the mane 6 characters. She is white (although she actually is a very light blue despite her looking white) and the blue/aqua/purple curly hair, with 3 blue diamond gems as her cutie mark.
A pic just in case:
http://img3.wikia.nocookie.net/__cb20120720153157/mlp/images/8/8f/AiP_Rarity.png
That pony is called Rarity
Her name is Crystal Lace.
Her name is Diamond Rose in My little Pony Friendship is Magic.
In My Little Pony, a ponies get their cutie marks by discovering the special talent for which they are destined.
Earn your cutie mark(s).
The cutie marks in My Little Pony are the images on the ponies' flanks. In The Friendship is Magic series, the cutie mark representsa pony's special talent. A pony starts out with a blank flank, the cutie mark appearing when that pony discoveres his or her talent.
The orange pony with glittery pink hair and a fireworks cutie mark is called 'Sparkleworks' .
Her name is Diamond Rose in My little Pony Friendship is Magic.
Derpy Hooves' cutie mark consists of a cluster of bubbles.
Pina Colada
In My Little Pony, a ponies get their cutie marks by discovering the special talent for which they are destined.
The cutie marks in My Little Pony are the images on the ponies' flanks. In The Friendship is Magic series, the cutie mark representsa pony's special talent. A pony starts out with a blank flank, the cutie mark appearing when that pony discoveres his or her talent.
Earn your cutie mark(s).
In the current version of My Little Pony, cutie mark is a simple image that appears on a pony's flank. The image in some way symbolizes that pony's special talent and usually appears when she or she discovers that talent as a school-age foal.
The orange pony with glittery pink hair and a fireworks cutie mark is called 'Sparkleworks' .
My Little Pony Friendship Is Magic - 2010 The Cutie Mark Chronicles 1-23 is rated/received certificates of: USA:TV-Y (E/I)
In MLP:FIM Scootaloo does not yet have her cutie mark, nor is it known where she will get it. In earlier versions of MLP it is not revealed how or when any pony gets a cutie mark.
Her name is Golden Harvest, though she is often called Carrot Top by the fans.
chase snips and sails away about five times and do that until you get the unicorn pony.