Black/White Umbrellas do a very similar job to the silver. They are much less harsh though, scattering softer light over the same area as their silver cousins, although the light is diminished by almost a whole stop comparitively, so you'll need to turn up the strobes.
With a less reflective umbrella comes a less brutal shadow, and so, in portraiture, the black/white umbrella is often favoured, though both have their merits.
The catchlights are similar to that of the black and silver umbrella.
90cm Counterfold Fold White Shoot Through Umbrella
White Diffuser Umbrella's (also known as shoot-through umbrellas) are a favourite of all portrait photographers. They're inexpensive and quick and easy to set up. They produce a lovely, even, widely scattered, soft light. They can cause hotspots, particularly since they are the only umbrella which you shoot through, which makes the central part of the umbrella prone to being brighter than the light that scatters around it.
They still produce a slight halo on the shadows, but this is negated to a large extent by the diffusion qualities of the umbrella.
The most noticable difference when using a shoot-through, is the shadow areas on the face. The catchlights demonstrate the previously mentioned hotspot in the centre, but the quality of the light is much softer and more flattering.
The 90cm counterfold white umbrella packs down to a compact 16 inches allowing you to pack your strobe kit down into a smaller space. Great for portrait, product and food photography the 90cm counterfold does just what the others do. Only smaller