Once you reduce its thickness to 50 nanometers, light can easily pass through it, so that it no longer reflects light. Its color changes from gold to red, and it becomes an excellent material for pregnancy test kits. Once gold is manufactured as thin as 50 nanometers, it goes from being extremely stable to being extremely volatile, allowing it to be used in many different applications as a catalyst or activator.
例如，黃澄閃亮的金子，一旦縮小到五十奈米時，由於光線容易穿透，不易反光，因此顏色轉金為紅，可以作為絕佳的驗孕劑；等進一步縮小至五奈米後，原本「真金不怕火煉」、物性極為穩定的金子，此刻竟活性大增、躍動不停，可以作為用途廣泛的觸媒或活性劑。