black formal one shoulder dress Velvi - Kelli Midi - Stride through a day of compliments with the utmost confidence in the Lulus Graceful Elegance Black One Aleta One-Shoulder Long Black Beaded

Up until that point, Dianas style had been all pale pink and baby blue netting and sequins, she told British Vogue last year, and said that the black, strapless gown was Diana's first grown-up dress

The key

The Ruebelle Midi Dress features halterneck straps and a v neckline, an open back, an asymmetric hem and a silver clasp belt at the centre

Apply Common Sense Depending on your relationship with the hosts of the wedding, you likely have some idea of their customary level of formality and the nature of the wedding they would have planned

An elegant mix of black and pearl, with short, voluminous sleeves and a beautiful open back, luxury finishes