Implantation spotting, when it occurs, is typically very light, pink or brown, lasts under two days, and appears around 6–12 days after ovulation. But most people who conceive report no spotting at all, and most spotting is not implantation.
Other causes include a short luteal phase, ovulation spotting mid-cycle, hormonal contraception, cervical irritation after sex or a smear, polyps, and infection.
There is no way to tell from the colour or timing. The only thing that resolves the question is a pregnancy test taken on or after the day your period is due.