Peridot belongs to the forsterite-fayalite mineral series which is part of the olivine group. It is one of the idiochromatic gems, meaning its color comes from the basic chemical composition of the mineral itself, not from minor impurities, and therefore will only be found in shades of green. In fact peridot is one of the few semi-precious gemstones found in only one color.
They have highly sensitive blood tests that can detect the pregnancy hormone (hCG) a few days earlier around day 3 to 4 after implantation. Again, some women have had positive urine tests as early as 2 to 3 days after implantation and others have had to wait up to a few weeks.
Beyond answering the question implantation bleeding or period, a pregnancy test will always be the best way to ease your mind. Be sure to take the test after your regular period should have been and not immediately after the bleeding. Even if it is implantation bleeding, the pregnancy test will probably still read negative as hCG levels in will be insufficient. On average it takes about 48 hours to get even a faint positive test.