Mine lasted several days - think about 6. I thought for sure my period was starting. It ran the range from pinkish to dark brown. Always fairly light, though.
It's likely that I had it (you can see on my chart at 8-9 days past ovulation.) It was pink in the beginning and a little red, then trailed off to brown. Lasted a day and a half.
I had it, brownish spotting for about 2 days (what I normally have at the begining or end of a period). I thought I was getting my period and was so disapointed but happily not so much!
For me it was brown/ dark red-ish and lasted for about 5 days. I had a very early BFP so after it lasted for 3 days I thought something was wrong, but as it turns out nothing was and it can look different and be from anywhere from 1-7+ days depending on the person. I would suggest call your Dr. if your worried.
Re: ? about implantation spotting
I had it, brownish spotting for about 2 days (what I normally have at the begining or end of a period). I thought I was getting my period and was so disapointed but happily not so much!