ขอมูลทั้งหมดนี้ขอขอบคุณ อาจารย์อวยชัย สุภาพจน์ This Is not to declare that softer stones, including serpentine, can't be polished, but they need to only be polished with other stones of comparable hardness rather than combined with tougher stones. Wash the rock thoroughly with a scrub brush or aged toothbrush to remove any stubborn https://beediadiamond.com/catalog/polishing-stones