Very much like Mint Candy Apple, Lilacism is a firm favourite of most Essie polish users.
I really like muted shades and want to like this shade more than I do,
for me I prefer my lilac's to be more blue toned and this sadly is not,
that's not to say it's not a pretty shade because it is but it is not a special shade by any means.

Lilacism is a clean milky toned lilac polish that reminds me of OPI's Rumples Wiggin'
albeit a little deeper in tone but similar none the less.
I have the version from the diffusion line and found it to be fairly thin in texture
but applies fairly well and is opaque after two coats, it dries to a crème finish that has a lovely sheen.
Again I am not loving the wide brush that is in the diffusion line but hey ho you can't please everyone.
In terms of dupes I'm sure you would be able to find something pretty easily,
today I noticed a wide range of pastels in the NYC stand.

Essie diffusion polishes £7.99/15ml available from selected Boots and Superdrugs
but currently on a 3 for 2 via Superdrug - link.

Nail Polish Disclaimer - I will no longer be commenting on the wear of nail polishes
unless it chips instantly etc as I change my nail colour too frequently (sometimes daily),
to comment properly on the wear and as we all use different techniques such as top coats/base coats
I don't feel that my comments on wear time are helpful in any way.