Here's the standard Colt Detective Special grips.
This info is for Colt Detective Special ONLY, other Colt small frame guns like the Diamondback used other style grips.
Note the following:
From 1927 to 1933, the DS had the same square butt as the Police Positive Special. After 1933 they used a round butt grip frame on the DS.
From 1927 to 1950, all Colt small frame revolvers had a long grip frame.
In 1950 Colt introduced the aluminum framed Cobra and Agent.
The Agent was intended to be a deep concealment gun, so the grip frame was changed to a "stubby" square bottom grip.
The DS and Cobra retained the old style long grip until 1965, when to simplify production ALL Colt small frame revolvers went to the "Stubby grip.
Here's the difference on frames:
The early Colt DS grips from 1927 to 1972 were fully checkered Walnut with Silver Colt medallions.
After 1965, the DS grips overlapped on the bottom of the short "Stubby" frame to give a longer grip:
In 1972 Colt introduced the heavy shrouded barrel model with the wrap around "combat" grips.
Over the years, Colt also sold as optional, the Pachmayr "Compac" rubber grips with Gold Colt Medallions.
The last issue 1990's Detective Special had the Pachmayr grips as standard.