Collecting knives by Handle Color/Material
A slight variation in knife collecting, some people collect knives according to the knife handle material or color. For color, some examples include "White Linen Micarta", "Ghost Jade G-10", "Emergency Orange G-10" (pictured below). This is an interesting way as even non-knife nuts can immediately spot the way in which you collect knives. Not to mention it is a very eye-catching display of collecting!
Orange G-10 handle collection (Photo:Ragoligist - knifeforums)
For Handle Material, some people collect knives with materials ranging from natural to non-natural. Non-natural materials include G-10, micarta and rubber. Natural materials include abalone, wood, leather, stag and stone. For natural handles, it is best to match the tone of the material so that the whole collection looks quite uniform. Stag and wood can have different shades of color although they are from the same horn or piece of wood.
Matching Buckeye Burl handled knives (Photo:DJJ - knifeforums)
However, this is not very commonly done because of the difficulty in getting all the handles to match. It is also a rather costly way of collecting knives.