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.
It takes at least 2-3 days after implantation for there to be enough HCG in your system to be detected by the most sensitive test available, First Response Early Result. If you do test and it's negative, don't fret, just wait a couple more days and test again with the First Response Early Result. Good luck!