A pair of vintage collar studs, for fixing stiff, soft, or semi-stiff collars to tunic shirts.  These are old items - difficult to date exactly, but nearly all of them were made in the first half of the 20th century.  Each pair consists of a front stud and a back stud.
    
Some are made of mother of pearl, others celluloid, tagua nut (also known as nut-ivory), rolled-gold, gold-fill (these are both types of gold plating) or other materials.
The front studs have various devices, including pear-drop toggles, round toggles, split pins and butterfly pins.
Most of the back studs are rigid - a few have toggles.
Please see the photographs to see the exact design of each pair.

The studs will be supplied in a plain gift box.

Note: if you have not worn a detachable collar before, you may be wondering why these are called "pairs", when they are clearly not the same length or design.
The answer is, that the front stud has to pass through more layers of starched cotton than the back stud, so it has to be longer.
Obviously, neither collar stud will actually show when you are wearing them, so the design is very much a matter of convenience and personal choice.

Condition
USED vintage collar studs.
These studs are in working order, but they are old.
Most of them were made in Edwardian times, or the 1920s and 1930s.
They have some small marks from normal use, and some of them are a little stiff, but they do work.
These are not "matching pairs" - each pair consists of a front stud and a back stud, as shown in the photographs.