Hello Stefanie,
For your info, Mauser did some Luger with ivory grips. I have in my collection two Mauser Parabellum with ivory grips.
It was possible to order the gun directly from Mauser with ivory grips with different kind of engravings.
For sure now these pistols are really expensive and the probability to find out original Mauser ivory grips is really scarce.
If you want to see some Mauser Parabellum with ivory grips, just look at my web site and click on "Mauser Parabellum Area".
www.lugerlp08.com
Have fun,
Mauro