Welcome Jor-el. I agree whole-heartedly with Alam Shah, though i might also add another book to the short list that he mentions in the list on the link John provided.
The Kris: an earthly approach to a cosmic symbol.
Auth: David van Duuren.
Published: 1998, Netherlands, 1st Edition
Format: Hardcover, 95 pages,
ISBN: 907318732X
Comments: ***** Another good primer with good color photos.
Scholarly account of the kris - its distribution, history, function and production. The
significance of the design and motifs on the blade, hilt and sheath and the regional variations are all described with the aid of illustrations from the Royal Tropical Institute Collection, Amsterdam.
Certainly some of the best photos you will find in a keris book as well.
However, an understanding of the keris can never be reached in a vacuum. These authors only give you a very small glimpse into Indonesian culture so i highly recommend you study whatever you can find on the culture itself apart from that the keris. Skeat's "Malay Magic" is a good one and "Visible and Invisible Realms" by Margret Wiener is indespensible.