The depth is the constraint
The pieces here run 12, 15 and 16 inches deep, and that narrow band is the whole definition of the form.
Deeper than sixteen and a console starts obstructing the hall or the room it stands in; shallower than twelve and it holds nothing. Everything else about a console follows from having to be useful while taking almost no floor.
Length is where they differ
The lengths here run 40, 48, 49 and 63 inches, against heights clustered between 30 and 36.
Those lengths are chosen against a wall rather than against a room: a console usually sits under a mirror, between two doors or along a hall, and the length is set by that opening. It is the figure to measure first, and the one that rules most pieces out immediately.
Marble and travertine
Marble leads the materials with travertine behind it, in whites, blacks and a beige.
Both are being used as furniture rather than as surfaces, which changes what matters about them. A console is seen from the side and from above, and its edges are at hand height, so the thickness of the top and the way the stone turns a corner are more visible here than on any floor. Marble furniture is the wider range.
Polished carries them
Polished leads the finishes with a honed group behind it.
On furniture a polish does something it does not do on a floor: it makes the piece read as an object rather than as a surface. A honed console is quieter and reads closer to plaster or concrete, which suits a room where the stone is not meant to be the event.
The named stones
Calacatta, Carrara, Arabescato and a Light run through this small range.
Those are the boldly figured marbles, which is the opposite of how they are usually deployed. A Calacatta floor is a commitment across a whole room and needs laying out piece by piece; a Calacatta console is one object carrying one piece of veining, chosen and seen as a single thing. It is the easiest possible way to have a dramatic stone in a house.
The heights and what they are for
The heights here cluster between 30 and 36 inches, which is a wider band than it looks.
Thirty inches is table height and the piece reads as furniture somebody might sit at. Thirty six is counter height, and at that point a console behaves like a serving surface or a hall counter instead. The six inches between those two changes what the piece is for more than any other dimension on it.
Where a console goes
A hall, an entry, behind a sofa, under a mirror, along a landing and against the wall of a dining room.
It is the piece of furniture that fits where nothing else will, which is most of the reason the form exists and why it has survived unchanged for so long. Marble furniture covers the other stone pieces in the range.