You are asking the impossible here Oddie. As you have probably been told by lots of other florists- there is no such thing- unless you have dyed roses (but I wouldn't recommend them as the dye could easily come off and ruin your expensive clohthing).
Your options are-
1) silk flowers- you'll find a shade of cyan in a good stockists, either add a couple of the cyan coloured silk flowers into a fresh flower bouquet or go the whole hog and have all your flowers in silk.
2) steer away from trying to match cyan at all- you have picked orange as your accent colour, orange will be a lot easier to match- maybe you could soften the use of orange in the bouquets by using a touch of peachy toned flowers.
3) an all white/cream colour combination for the flowers picked out by a cyan accesory ie a butterfly, beads or feathers. Cyan ribbon could be used around handle of the bouquets.
Remember, the colour you are describing sounds quite dark- in the photographs the dresses will provide a large block of the cyan colour you want already- putting cyan flowers against cyan dresses and the effect may get lost. You can bring in the colours throughout the rest of the wedding on your tables (napkins, favours, balloons?) and cake (a ribbon tied around the cake?).
Good luck Oddie.