This old expression has new meaning in our modern stylistic era.
In World War II, which may have been the origin of this idiom, almost all sinks were porcelain coated steel, an invention of the Chinese to make steel, waterproof and scratch resistant. Porcelain is still commonly used but the number of other choices abound.
In the last few decades the kitchen sink of choice has been Stainless Steel. It is easy to maintain and stay shinny, doesn't stain and minor scratches can be buffed out simply, with steel wool. Stainless is measured in "Gage," the lower the number the thicker the metal and its increased wear ability. Nonetheless, the shape and size of typical sinks did not change significantly.
A major change began when sinks no longer need a ring ( dubbed "Houdini Ring" because they were difficult to install) to hold in place and seal properly. Probably the introduction of silicone made sink installation much easier. Then under mount sinks were introduced for granite and marble tops. Integrated sinks also became popularized first in vanities and later in solid surface man made materials, that are poured into a mold.
Today there are many sizes, shapes styles, colors and materials that can be purchased for your kitchen or bathroom sink.
Porcelain: White is standard but many color choices are available. Underlying steel is also measured in Gage and priced accordingly.
Shapes: traditional, square, round, "D", oblong, wing, butterfly, "L" and my unusual and interesting shapes.
Finishes: shinny, dull, brushed, penalized, hammered etc.
Style: top mount, under mount, farm, pedestal
Size: small rectangular are known as bar sinks, approx 16x16 are prep sinks,
Larger are kitchen sinks
Copper /Brass: There is renewed interest in copper and again they can be shinny, dull or "Patina." Patina is an aging of the copper where it turns dark and can grow bumps as it reacts to various chemicals. I have seen cooper turn blue-green from chemical exposure. You can buy new sinks with Patina to give it an ancient look.
Solid Surface: often there are integrated sinks poured with the counter top, but the can be purchased & installed separately. If you are looking to introduce a sink color, this may be an option.
Cultured Marble: Introduced in the 1950's a man made poured product which wears well available in many colors, primarily used today in bathrooms. It maintains its shinny finish well and is inexpensive to manufacture. It is brittle however and does not hold up well to heavy items dropping on it. Moreover, because it can stain from many foods it is not generally used in the kitchen.
Glass Bowl: Often used with vanities or hand washing stations, these stylish bowls sit above the counter rather than recessed. They often require more clean up as water splashed outside of the bowl has nowhere to go.
Acrylics: These are poured/ molded products that can have a shinny or dull finish. Think of these composite materials as a cross between fiberglass and plastic, as they have a plastic look but the strength of fiberglass. Standard is an off white but may colors and shapes are available (Bathtubs in acrylic are very popular, for example most Jacuzzi's).