Convert from nanogram to momme [Japan]

Unit Definition (nanogram)
The nanogram is a metric unit of mass equal to 10E-9 gram, or one millionth of a milligram.

Unit Definition (momme [Japan])
The momme [Japan] is a traditional Japanese weight unit corresponding to the Chinese mace. Jewelers continue to use the momme to measure the weight of cultured pearls; for this purpose it equals exactly 3.75 grams (about 0.132 ounce) or 18.75 carats. The unit is commonly pronounced "mommy" in English.