I'm sorry - it will disappear but it will take weeks.
Your experience is why we don't sell those needles anymore, and have designed better needles.
The problem with our previous needles is that the tolerance was too high, meaning that some of them were about 2 mm long or sometimes even longer. We did manual inspection of all of them but sometimes a too-long one slipped through. The result was that occasionally (1 in 100 customers perhaps) there was severe bruising reported and also subcutaneous bleeding.
You could perhaps photograph the needle next to a ruler with a camera on macro setting, then you can see exactly how long it is. I suspect you got a too long a needle, or your skin at that spot is particularly thin, or you have veins right below the surface (lack of subcutaneous fat).
Our upcoming single needles are all 1.8 mm long.
Please do not worry about this. Bruising and the perfusion of blood plasma is strongly associated with dramatic skin improvement, when needling. It will take time for the coagulated blood to be reabsorbed by the body.
Related forum posting:http://forums.owndoc.com/dermarolling-microneedling/single-needling-bruises/