When brides call me for help the most frequent topic I cover is how to pick the right colors. I thought it would be helpful to communicate the basics and go into a little more depth in this area.
First, there is truly nothing in the world quite like the brilliance of white diamonds. A topper in all Crystal makes a statement all its own. It goes beautifully with almost any cake and is sure to please. For a more conservative look it's definitely a safe way to go.

Single Initial Cake Topper

Marilyn - Crystal

Monogram Cake Topper

Wendy (S), Georgia (LC) - Crystal

Having said that, making the decision to add in color doesn't have to be scary! If you want something with a little more color, but aren't going for a dark dramatic topper either there are subtle ways to find a middle ground. Silk and Crystal AB, or any other crystal in the pastel family, can be added to tone down the brightness of an all Crystal topper. Gold Shadow and Silver Shade are soft metallics that are also not overbearing in color. Additionally, for a romantic look and the old-fashioned at heart, Jonquil AB adds a unique "antique" look.

Single Initial Cake Topper

Melissa - Gold Shadow, Silk, Light Rose

Single Initial Cake Topper

Marilyn - White Opal, Crystal, Crystal AB

Contrast is the key to picking a good color mix. Even if you have a wide range of colors in your overall wedding pallette, there is no rule that says your topper has to include them all. In most cases I actually discourage it! Choosing colors with the right level of contrast is the trick. It's just as important as matching the right color!
When choosing colors to go together, first determine whether or not you like the "polka-dot" look. A "polka-dot" look is a very high level of contrast. If this is what you're after, then there are really no guidelines -- picking your colors will be fun and easy! For cute cakes or whimsical fonts, like Giselle or Paisley, I'm all for polka dots... the more varied the colors, the better!

Monogram Cake Topper

Florence (T) - Rose, Light Rose, Light Rose AB

Georgia (HB) - Rose, Light Rose AB, Crystal AB

Single Initial Cake Topper

Paisley - Emerald, Crystal, Amethyst

Single Initial Cake Topper

Marilyn - Vintage Rose, Burgundy, Crystal

For more formal events that call for a more classic styling, it may be suitable to reduce the contrast in order to minimize the "spotted" look. The idea here is to pick either a single color, a single color along with its AB counterpart or better yet, if it's possible with the Swarovski collection and your theme, to select colors that are only a few shades apart from one another. Up close, three or four complementary colors will add a wonderful texture to your topper, while still maintaining a single overall color from afar.

Single Initial Cake Topper

Vivica - Light Sapphire

Single Initial Cake Topper

Sidney - Fuchsia, Fuchsia AB

Single Initial Cake Topper

Jasmine - Silk, Light Peach,

Light Colorado Topaz, Gold Shadow

Single Initial Cake Topper

Custom Font - Light Colorado Topaz,

Silk, Light Peach, Gold Shadow

Keep in mind that you're not just designing a topper, rather the final element of your cake table. The accent decorations may sway your decision and make the color "dilemma" a no-brainer. My first question is always: "What does your cake look like?". A great idea is to pick a topper color that will help it stand out against the frosting or flowers decorating your cake. If you're having a Red, Black, and White event with red roses topping the cake then a white topper would look magical atop the roses whereas using reds in the topper risks possible clashing. For the same reason, if your cake is chocolate frosted I'd consider leaving Smoked Topaz out of your topper.

Monogram Cake Topper

Brittany (V) - Light Siam, Fire Opal, Sun

Mary (DB) - Fire Opal, Sun, Gold Shadow

Monogram Cake Topper

Wendy (T) - Siam -- Georgia (KR) -

Topaz, Light Colorado Topaz, Gold Shadow

Incorporating Pearl stones in your Topper can be beautiful... when done carefully. Since it is only available in 2 sizes, compared to 3-5 sizes for crystals, I can only use pearl as an "accent stone". It can't be used by itself or be the focal point of the topper.

Monogram Cake Topper

Vivica - Gold Shadow, Silk, Cream Pearl

Monogram Cake Topper

Wendy - Light Rose, Siam, Cream Pearl

Here are some of the most requested color palettes and some ideas on how to achieve them. Click on the link for what you're after to see the examples. Keep in mind, these are just a few ideas, the possibilities are endless.
Of course, this is just a start. If you're still on the fence, or want to see some color samples in person, don't forget: I'm just a phone call away...

Black & White

Pinks

Reds

Tiffany Blue

Browns or Golds