Fragrance Oils are synthetic materials.  Depending on what materials a certain fragrance oil (FO) is made out of, the color of the oil can vary from FO to FO.  Most fragrance oils are a shade of yellow.  Others can be a hue of green, orange, red, and the like.

Candle making is a science.  The right amount of wax, FO,  candle dye, correct size wick, etcetera all matter in the formation of a nicely burning (and looking) candle.  New fragrance and color combinations should always be tested to make sure they are safe, and to ensure it is the look you are going for.

It is good to note that sometimes a FO and candle dye can mix together and form a candle color that is different from the original shade.  A prime example is below.  The pinecone on the left was dipped in Paraffin wax dyed with Red Liquid Candle Dye.  To add a tantalizing scent, Cinnamon Fragrance Oil was added to the pinecone on the right.  Even though the pinecone on the right  used the same red colored wax that the 1st pinecone used, the fragrance oil altered the color and made it pink.