Factory-pressed CDs, DVDs and BDs look nearly identical.
CD-Rs are yellowish/greenish, while DVD-R has a beautiful red dye. Sometimes, it is also dark cherry red (eg. GSC003).
Why does that beautiful dye look different for each manufacturer? Does it depend on the maximum speed? We also have some old Speer DVD-R’s with ×4.
DVD+R looks rather purple.
DVD-R DL looks red, sometimes even brown, while DVD+R DL looks blueish red (XLynq looks blue).
BD-R looks as dark as CD-RW/DVD-RW/DVD+RW.
DVD-R/RW has a small ring at the inner data edge, that is missing on DVD+R/RW.
In 2012, in Iran, I also saw a black and a red CD-R. I wonder, how they were made. The red one looks like a DVD-R.