The lid of the box is inscribed with a quote from Shakespeare’s Othello:

This is from a passage all about the value of keeping one’s reputation (and the worthlessness of taking another’s reputation) the source of Jones’ and Zambaco’s ultimate crashing downfall in their relationship in c. 1870 when Jones changed his mind about leaving his wife for Maria, prompting Maria’s attempted suicide.

There is a french quote around the box’s edge is by Alfred de Musset (the, “French Oscar Wilde”).

This translates as “people who are spirited (Maria?) or “happy/jocular (Burne Jones?) can’t be successful lovers”

So it is a very odd gift – a heart not of love but of finished love or unrequited love. That fits Burne Jones relationship with Zambaco perfectly but it does not preclude many other possible owners of the box of course.

However, I think the odd blue enamel on the lid is an M (for Maria) designed within Greek architecture – Zambaco was a French speaking Greek. It also has some resemblance to the backdrop of Jones famous painting of his love affair “Love among the ruins”. In 1894 he repeated that painting in oil.

Finally there were letters between Jones and Zambaco sold at Dreweatts in 2016 (March 17, lot 104) which showed Jones was still writing to the Zambaco family as a friend and passing them small gifts, at least as late as 1888. So a gift in 1894, even 20+ years after their affair ended, is plausible.