Ploy (พลอย) is the Thai word for "gem" or "gemstone" — particularly the colored stones (rubies, sapphires) for which Thailand is famous. A popular modern Thai feminine name.
Ploy is widely used in Thailand.
Ploy 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 Ploy reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.