It is fairly difficult to introduce coloured framing materials to black and white images. It can be done especially if the framing is selected with a room's decor in mind and the pictures to be framed are creating a theme in a given room. However it isn't the norm and hence grey is a colour that we often use for framing monochromatic pictures. Perhaps surprisingly, monochromatic pictures are often the most difficult of pictures to frame as it is all about matching the grey tones within a picture. So we have just introduced a selection of mouldings to give a wider choice with regards to the shade of grey. It isn't quite 50 shades but these mouldings have been very useful, especially with lighter pencil drawings where the more subtle shades are effective. The extreme colours of either black or white could have been selected but these can be too eye catching (especially black) and could dominate the picture.
The mouldings also have a larger and a smaller profile for some of the selection which is always useful for several pictures of similar colour but varying size.