Its interesting that Roy mentioned the optional front sight blades.
The blade he is referring is a thin blade with a bead across the top of
it. The rear face of the blade could have an ivory, or a brass (gold) bead.

One of the blade available was the Lyman blade. Sometimes they had an ivory, or
gold bead on the rear face of the top bead.

The blade on this revolver is one that was used for years. There is a name
for it - it has no bead on its top edge.

Later, Mike Priwer