[A. G. Maisey]

Not a bad keris. Not bad at all.

Based upon what I can see in the pics, and accepting that this opinion could change if it were in my hand, I would give this blade stylistically as Mataram Sultan Agung, but that is not to say it necessarily is M'ram SA. To get a good fix you need it in the hand.

Wrongko is as Rick said:- Madura.

Hilt must be changed, and the mendak is only so-so, but as a first keris, its a nice choice.

EDIT
Since writing the above, it has been pointed out to me that my comments on classification of this blade could easily confuse somebody who is not particularly familiar with stylistic variation, and after thinking about what I have written, I am inclined to agree.
The sweep of the gonjo, the square outline of the blumbangan, the kruwingan, the pronounced and lengthy ada-ada, and the length from the tip to the first wave behind the tip are all in the style of a Mataram Sultan Agung blade, as it would appear prior to erosion, however, the material is not possible to judge and the ron dha is not within the parameters of a Mataram SA ron dha.
I hope these further remarks make clear my meaning.