The first Bowie knife was made by myself in the parish of Avoyelles, in this state (Louisiana), as a hunting knife, for which purpose, exclusively, it was used for many years.
Rezin P. Bowie, Planters Advocate: August 24, 1838.
Describing the knife Jim used at the Sandbar fight, Rezin Bowie said, "The length of the blade was nine and one-quarters inches, its width one and one-half inches, single edged and not curved (i.e. no clip aka false edge)" ”¦quite different from the Bowie knife as it came to be recognized
Go here to see more - and be sure and click on the underlined names for pics of the earliest known bowies..
http://www.tamu.edu/ccbn/dewitt/adp/history/bios/bowie/knife_like_bowies.html
The earliest Bowies had single edge blades basically in the shape of what we call a French chef's knife with a dropped edge style blade and no clip. They either had no guard or a single guard like the Searles Bowie made for Rezin, not a double guard.
The clip point style blade with double guard first shows up in the early 1830's and was made as noted from then on in huge quantities by the English, but the American firm of Sheffield Knifeworks, Phila, Penna, was also making clip pointed, double guard Bowies beginning in 1831.
You probably have the latter style blade with clip point and for those PC handle material will depend on where and when made. For English made knives, African Blackwood, Gaboon ebony, Sambar Stag, bone, and horn (mostly black water buffalo from India) and real elephant ivory were very common handle materials. Mastodon ivory was unknown at the time except maybe in Europe. So called pre-ban real elephant Ivory is still available, but is expensive as noted.
On American made Bowies it gets a bit more complicated since you have professional cutler made knives as well as so-called primitives made by local blacksmiths. For these handles run the gamut from the same materials used by the English, along with locall products such as maple, black walnut, hickory, and deer or elk antler.
For the best imitation Ivory check out a product called Tru Ivory. For a similar look to ivory in a natural material, but without the price check out giraffe bone, a very dense bone that works up excellently. For guards the most common of the period is German aka nickle silver with brass coming in a distant second and used more widely on American made period Bowies.
IMO - a suggestion spend the money to get the book The Bowie Knife Unsheathing a Legend by Norm Flayderman. For around $80.00 bucks you get 520 pages of gorgeous color images of real period Bowies as well as a ton of well researched info that helps lay to rest much of the mythology surrounding Bowie and his knife. You amy also be able to get it via your local library.