Illamasqua Speckle is a very cool-toned, light-medium lavender with a glitter finish. It is a limited edition nail lacquer that retails for $17.00 and contains 0.5 oz.
Illamasqua Speckle Nail Varnish ($16.00 for 0.50 fl. oz.) is described as a "speckled lilac." It has a soft, pale lilac cream base with flecks of small black glitter and larger hexagon-shaped black glitter. I don't know of any dupes in particular for this shade (Deborah Lippmann also has speckled polish but nothing in lilac). If you have a top coat with black glitter already, you might try using Essie Bangle Jangle, MAC Little Girl Type, Nubar Purple Aster, or Zoya Marley has a base color, as they are similar.