I have a piece of white uranium glass that doesn't seem to glow right. What gives?

White and cream color uranium glass is known as custard glass. While it generally glows fairly bright, it sometimes does not have the vivid green of other colors of uranium glass. Some pieces can have a softer green glow. Some pieces can look like they barely glow at all, and not very green whatsoever. Those can be difficult to pinpoint as uranium glass unless they can be measured on a Geiger counter. Custard glass of this kind is not very common.