Quartz (rock crystal) faceted points. April birthstone.
Clear quartz points (rock crystal), that have been cut such that they stand securely on their own. The left one actually has a slight yellow/orange tint so could be classified as pale topaz. The middle one has interesting internal flaws that also cause it to show a rainbow effect in some lights, shown in the photo. Rock crystal is a more recent British birthstone for April.
Please note - as natural, albeit polished, items these are not symmetrical but they all have at least one orientation that has them standing nice and vertical as shown.
Left: Approximately 3/8 inch (0.95 cm) wide and deep, 1 inch (2.5 cm) tall. #5112
Right: Just under 1/2 inch (1.3 cm) wide and deep, just over 1 inch (2.5 cm) tall. #3579