The chrome three-prong support is typical of the lamps that were made by Webb & Corbett. The probability is that the shade would have been a glass tapering cylindrical form (imitating a standard cloth form shade) that would have been acid etched in order to diffuse the light. There would then have been a cut and polished pattern in order to decorate the shade.
In my opinion it is unlikely that the shade would have been domed as, from memory, all the 'Art' cut glass (Modernistic/designer cut glass) that have domes are used above a cushion foot. In other words a glass cylinder rising up into a dome top (diffused, etc. as above), set upon on the same three-prong style support, which is fixed to the bulb holder above the cushion base - which in turn usually has a star-cut base.
Other examples are spherical bases, again with same three-prong support having a tapering cylidrical shade (as described above).
Sadly, in my experience, finding this style of replacement shade is impossible!!
NOTE: These observations do not apply to traditionally cut glass two-piece lamps.