Our thanks go to Marshall Ketchum for this explanation
A few days ago there was a discussion of Steuben’s white glasses and, I think, the request for more information. I am willing to give my definitions of these glasses. I am going to include Ivory because the Ivory and Ivrene names are similar enough to sometimes cause confusion. I dislike using the terms “never” and “always” because when you do someone can come up with an exception. I am going to do so here for simplicity recognizing that there may be exceptions.

IVORY
Ivory is a translucent yellowish glass that is yellow in both reflected and transmitted light. It is never found irridized and is never found with an acid etched signature.

IVRENE
Ivrene is a translucent chalk white glass. It is always found irridized. When signed, it is signed with an engraved block letter signature. It is never found acid etched as its chemical composition will not allow it to be successfully acid etched. There is some evidence that when Ivrene was used in lamp shades it was called Marbelite.

CALCITE
Calcite is an off white translucent glass. It is off white on the yellow side in reflected light and has a soft warm yellowish glow in transmitted light. It is always irridized. When used in lamp shades or as a Calcite dome it can be found plain or decorated with other types of glass. It is also commonly found acid etched. When made in something other than a shade or dome it is never found plain but is always decorated with some other glass. Calcite was commonly used as the base for Decorated Red and Decorated Green Aurene pieces. When signed as a shade it is signed with an aluminum ink stamped fleur-de-lis on the inside of the fitter rim. When made as something other than a shade it is rarely found signed but acid etched signatures are known.

ALABASTER
Alabaster is a white translucent glass that can be found plain or decorated with other glasses. It is never irridized. It is commonly used as the base for many acid etched pieces and in those applications it may be up to ½ inch thick. When thick it may appear to be almost opaque. When used alone it will generally be much thinner and appear more translucent. Alabaster may be found signed with any of the common signature styles.

FLINT WHITE
Flint White or as it seems to be called in the Carder formula notebook “White for Flint” is a translucent glass that seems to be a bit “more white” and more dense than Alabaster of the same thickness. It is never irridized. Flint White is most often found as the contrasting color for Light Blue Jade.

To create more confusion the factory records for at least shapes 2557, 2597, 2618 and 2655 list it as being made in a “white glass” without further definition. It is unknown, at least by me, if it is yet another white glass or if the individual who entered it into the records didn’t know which of the more common white glasses was used.