【机】 蓝黑墨水

信件应该用黑色或蓝黑色墨水写在信纸上。

blue-black

blue-black ink

alizarin blue-black nb

blue-black【科技】;mazarine【科技】;navy blue【科技】

blue-black

alizurol blue-black

alizarin blue-black

acid alizarine blue-black