Kajol (काजल) is from the Hindi-Sanskrit kajal — the traditional black kohl eye-cosmetic used across South Asia, the Middle East, and North Africa for over 7,000 years; the word is also used poetically for darkness, eyes, and beauty. My Name Is Khan (2010) — premiered out-of-competition at the Berlin International Film Festival; among the first Bollywood films to be widely distributed in the United States. Founded the Kajol Foundation supporting underprivileged children. Kajal as a cosmetic is the namesake of dozens of Indian products and a top-1000 baby name in modern India.
Kajol does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Kajol reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.