It's watercolour with bodycolour, otherwise known as heightened white
There appears to be sun damage - some unusual darkened areas. " Blommers " has confirmed the picture was subjected to direct sunlight for a long period.
There's also a significant closed tear where the signature is
There's another which has been covered by " lightning " / more heightened white
The signature is slightly different, however as people age their writing changes.
The only way to attribute this properly would be to remove it from the frame and examine the type of paper used, age etc
The auction prices vary greatly because of auction house location and clientele, how collectors view the piece ( the auction house may have catalogued it as being by the artist but collectors and experts may think it is a " follower " of that artist ). Also the provenance - paintings which have been part of museum collections or displayed in prominent, public places are often worth far more than the average example )
Below is a Blommers watercolour which fetched $15,000. Better scale and detail, more " movement " and the signature is more flamboyant and in keeping with the artists regular signature
On findartinfo.com there are 6 pages of results for this artist. With this being a prolific artist who painted popular, attractive subjects then there will been many homages or copies on the market. I realise the original poster is convinced this is an original but a few things
a ) He didn't buy it
b ) He's asking people's opinion.
c ) His grandmother may well have acquired this genuinely believing it to be original but even in the early 20th century there will have been pictures bearing this signature that will not have been originals.
