A spell candle is a small candle, usually about four inches, in a colour chosen for an intention. That is the whole of the definition. Everything else attached to them — which colour means what, which day to burn them, what to do with the stub — varies so much between traditions that no single version can be called the correct one.
The colour lists disagree with each other
Green for money, red for love, black for banishing — these turn up so consistently in modern books that they read as ancient. They are not. Colour correspondence tables were largely systematised in twentieth-century occult publishing, drawing on ceremonial magic, folk practice and a fair amount of the authors' own preference. Compare two books and you will find disagreements: purple is spiritual power in one and ambition in another; white is a universal substitute in one and specifically lunar in the next.
This is not a reason to ignore them. A correspondence works because it fixes your attention on one thing, and a colour you have chosen deliberately does that whether or not a book agrees. It is a reason not to worry that you have picked the wrong one.
Why they are small on purpose
A spell candle is sized to burn out in a single sitting — an hour or two — because a great deal of practice assumes the candle is not left half-finished. If a working is meant to be completed in one go, a candle that burns for forty hours is the wrong object.
It also means you can leave one to burn down safely in a way you cannot with a large candle, provided it is in a proper holder on a heatproof surface and not left unattended.
Dressing a candle
Dressing means rubbing the candle with oil, sometimes rolling it in dried herbs, before lighting. The conventional direction is from the middle outward to send something away and from the ends inward to draw something in, though — as with colours — this reverses depending on whose book you are holding.
Practical warning that the books tend to skip: dried herbs on the outside of a candle will catch. Keep them below the wick line, use very little, and do not leave a herb-rolled candle burning in another room.
What to do with the remains
Traditions differ and none of them is binding. Some read the shape of the leftover wax, some bury it, some bin it without ceremony. What matters practically is that leftover wax in a metal holder is a nuisance to remove — put the holder in the freezer for twenty minutes and the wax lifts out in one piece.
Plain candles → · Setting up an altar → · The crystal library →