aljdewey, not an expert here, but I've definately seen enough radiants (as square as I can find them). The parameters me and my BF are looking for make it so much harder, but the stones that we have seen have been badly cut because there is no uniformity in this stone. Patterns have varied from so many cut styles like a princess pavillion, to star bursts, to brilliant cuts (like a round brilliant) to everything in between.
Honestly I have so far seen 6 different variations of cuts in over 20 different stones.
Imagine the lack of standards. Now compound that with the "improper" dimensions of a large table (for a nice larger looking stone), or the overextended depth, with hidden carat weight.
I have seen the proportions so distorted on these stones because cutters have yet to perfect the dimensions, and the industry has yet to define the proper"ideal" standards. You have cutters in India, cutters in Canada, New York, Amsterdam, Africa, Israel, all with their own "interpretation" of a radiant. No wonder these stones are so varied!
Now consider that a "properly cut" radiant in theory would have the brilliant cut of a round diamond on the bottom, the wide table and shape of a princess (or emerald), and in theory calculating proper angles for the crown and pavillion, determining a proper percentage for the depth and table, one SHOULD achieve a brilliant stone, second only to a round brilliant. In theory.
Looking at a princess cut bottom radiant today, compared to a more common "radiant" cut stone next to it, I noticed the facets made the Princess cut stone look well, like a princess with the angular facets, and it had those sharp pointed sparkles. The radiant cut stone actually looked like cracked glass (like IceLady had pointed out before), which added little sparkles all over the inside depth of the stone. It also had better fire and Scintillation than the princess cut stone. Now consider this stone was not even properly cut and can at best on average be considered a 3A all in all.
aljdewey, I KNOW there are phenomenal radiant stones out there that can outsparkle and outshineany other fancies. Finding it is the key, but keeping your color, clarity and size options as open as possible, may offer a better time in finding it. Lord knows, limiting yourself as much as possible in these parameters makes the search so much worse. If your standards are ridig, then keep your eye open and be patient. But I recommend the radiant hands down (next to the RB, of course) to anyone looking for a fancy stone with Brilliance, Dispersion and Scintilliation with some shape!