Rosewood or teakwood?  

Looks like teak to me.
Looks like teak to me.

My gut says teak based on col...
My gut says teak based on color and density of the grain. But hard to say from photos.
Plus this is what the Rosewood one looks like.\ http://www.norepro.co.uk/furniture/graphics/grete_jalk_rosewood_sofa_cha...

Teak, teak, and
teak. Rosewood may not always have a purple-and-black coloring, but it will always have a cooler tone than the orange of teak -- in my experience. The "orange" with brown grain is a dead give-away for teak . . .
The patten of the grain is also typical for teak, here. And at the micro scale, rosewood has a finer texture, a denser composition.

Okay ...
... thanks to all of you, if I compare it to the link of Joshua, it should be teak in fact.

Teak
Indeed.

Rosewood! Are you all crazy?!...
Rosewood! Are you all crazy?! It's Rosewood.
Oh wait... It's teak.

I have this
Grete Jalk "teak" sofa. It is identical in every way.
I do however, believe there is some secondary wood, namely the lowest horizontal pieces (what's the correct word for them?) and possibly the legs as well. The wood in those areas did not react the same as teak when lightly sanded and oiled. The color did not return when oiled as teak does, and there is no question that my sofa came to me in original untampered condition. Even the feel of the wood and the color is a little different...
Afromosia has been mentioned in other threads as a secondary wood used in some Danish pieces. Does anyone know if this Jalk model came in all teak or rosewood only, or if secondary woods were used as well? I have as yet, not been able to conjure up any data...

These France & Son chairs were offered in teak, rosewood, beech and occasionally oak.
Apart from some of the more awkward shaped pieces of timber like the curved slats on the backrest which could often be laminated and veneered the timber was always solid.
They did not use secondary cheaper timber, however you will often be able to identify different cuts of the same timber used on a sofa or chair which has notably different grain characteristics.