Esmée's the correct female form of the name, btw; Esmé is the male form.
And, yeah, I know Esmé's been used for girls for ages, but the original bearer of the name (Esmé Stewart/Stuart, 1st
Duke of
Lennox, whose mother was French: see
http://snipurl.com/1mglc) was male... and we English-speakers don't (usually!) use
René, Desiré/Désiré, or Aimé for girls, we use the correct Renée, Desirée/Désirée, and Aimée.