Can i jailbreak IOS 6.1.3 on iphone 3GS or can i downgrade?

I have a iphone and i really want to jailbreak but 6.1.3 can't because NO ONE MADE 1 AND THEY WON't so icant update to IOS 7 when it comes out what should i do i don't have SHSH Blobs saved?

I don't know when IOS 7 is coming but once i tried to update my phone phone is updated but phone showing activation. So if you know about you can jailbreak otherwise first you should about updation or activation.

You can't officially upgrade because ios 7 won't be available for iphone 3gs and there's no untethered jailbreak available for iphone 3gs but you can still have semi tethered jailbreak and who knows the might be an untethered one for the device some day soon.
heres the instruction on the semi jailbreak:

http://www.jailbreakevasi0n.com/jailbreak-6.1.3-semi-untethered-ios-on-iphone-4-3gs-ipod-touch-4g/

http://www.evad3rs.net/2013/03/ios-613-untethered-jailbreak.html