Is this real crystal or glass?

It is K9 crystal glass, an optical-grade glass with added lead oxide that gives it extra clarity and sparkle. It is not natural crystal.

What size candle does it take?

A standard tealight. The holder comes in three heights, roughly 6, 8 and 10 cm tall, so the opening is sized for a single small tealight rather than a pillar candle.

Does the champagne color affect the light?

Yes. The tint warms the glow and softens the candle's own color, so a white tealight reads amber through the glass.

Can I put it outside?

It is best kept indoors. Crystal can chip and the finish can dull with weather, and an open flame in a drafty spot is a safety risk.

Hand wash with warm water and a soft cloth, and dry it fully to avoid water spots on the facets. Skip the dishwasher and abrasive cleaners.

It works as a small housewarming or hostess gift for someone who likes table decor. It is decorative, not a practical household item, so it suits that taste.