Believe it or not, it is actually easier to find a Regency cap than it is to find a fashionable Victorian bonnet. When this one was offered to me along with other pretty Victorian items, I begged the seller; 'even if I cannot buy anything else, please let me buy the bonnet!'
I had fallen for it in a major way.
Black mourning bonnets of the late Victorian era are plentiful. Everyone was in mourning! But to find an example with colour, and perfect in style for a particular era, with nothing removed and nothing added, is so difficult. Here is such an example.
We go back to the late 1870's and into the 1880's. The bustle era. Fuss and luxury fabrics were the name of the day, as were contrasting colours and decoration of all types. Ladies wore their hair to match their bustle gowns, with a slim silouette to the front and curls all around the face. 
If you have the book; 'Vintage Hats & Bonnets; 1770-1970' by Susan Langley 2009, the chapters on the 1870's and 1880's will show you several bonnets just like this, for example on page 114, the illustration from 'Les Modes Parisiennes' dating to September 1879. The young ladies visiting their grandma, with their tall and slim figures, are both adorned with bonnets of this type.
This one is covered with burnished rust silk velvet, that looks like red in some lights. The frame, of the alice band style, is heavily padded around the face, on a [wire?] inner frame. Most of the velvet is then covered in swathes of leaf shaped cream lace [Blonde type?] all across the sides and crown.
Wide cream silk satin ribbon with delightful picot edges forms a double bow to the upper crown and then twists and turns to form two upper ties that may originally have had longer streamers attached. We read that in the 1870's these ribbons would hang to the back, and in the 80's would fasten more often under the chin.
But to [literally] crown the bonnet, we have a silk velvet rose arrangement, with a main open rose, surrounded by rosebuds and leaves. Open up the main rose just a little and see the original pink colour of it, and find the charming stamens, still fresh as can be. The rosebuds have centres of cotton wool! The leaves around the edges are wired, so that you can move them into your favourite position.
In addition to all this decoration, the original tiny hat pins are still all there, decorated with three minute ball shapes, they can also be pulled out and moved according to taste. I could play with it all day!
The black silk lining is exactly how it should be for the period, and all in all, here we see a most original Victorian bonnet for a bustle ensemble.