Sweden 1858 - 24 Ore - Does This Stamp Have A Watermark?

I've passed a fairly profitless afternoon trying to view watermarks on my classic Swedish stamps. I've had very little luck, with the possible exception of this one, a 24 ore stamp from 1858, which appears to have a watermark consisting of diagonal lines. This is the stamp in question:



Hopefully, you can see what I'm talking about from the following two scans. Reverse:



Reverse (solarised):



Does anyone know what sort of watermark this stamp is suppose to have, if any? If it does have a watermark, does it consist of diagonal lines?

All assistance greatly appreciated!

Jimjam, I don't believe that Sweden used watermarked paper until 1891.

I think I read something like that too somewhere. However, I cam across a website today that lists some very early Swedish stamps with watermarks consisting of 1, 2 or 3 vertical lines. This made me go back and examine all my older ones.

Sounds like what is in U.S. stamps called a "stitch watermark". These watermarks are unintentional from the rollers in the paper making process and are normally near the edge of the paper.

These stamps had a crown ornament watermark in the corner of each sheet but I've no idea how big it was or whether they appeared on any of the corner stamps or not. Some also had two parallel lines at the sides of the sheets.

Thanks Russ and nigelc. I went back to the website I was talking about and it seems they were referring to something called 'black' stamps, apparently test stamps released onto the market in very small numbers. It seems that these were watermarked.