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What is Rock Sugar?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

Rock sugar is a form of sugar composed of very large sugar crystals. People may also hear it referred to as “rock candy,” referencing one very popular use for it. Many candy stores and some markets sell the crystals for a variety of uses, and it can also be easily made at home.

When rock sugar is made, it begins with heating water and adding sugar to it in order to create a supersaturated solution of two parts sugar to one part water. In this supersaturated solution, there is so much sugar in the water that the mixture cannot remain in a liquid form, and sugar starts to precipitate out of the solution in the form of crystals. As the water evaporates, more and more sugar crystallizes, and the crystals typically grow quite large as long as the mixture is not disturbed. The end result is a cluster of very large sugar crystals.

Woman baking cookies
Woman baking cookies

Most companies and cooks add sticks or weighted strings to their sugar solution when they make rock sugar. These surfaces provide a space for seed crystals to start, encouraging the rest of the sugar to adhere to these crystals and forming clusters that are easy to handle. The use of strings or sticks also promotes faster crystal growth, ensuring that they are ready within a few days.

People have been making rock sugar for centuries. It appears to have originated as a candy in the Middle East, where it was often flavored with things like orange and lemon water. Sugar was once relatively rare and quite expensive, so candy made from pure sugar was a desirable sweet treat. Modern rock candy continues to be flavored and colored with an assortment of ingredients to make it more interesting, and it is a popular sweet in many regions of the world.

In addition to being used for candy, rock sugar can be used in other ways. It makes an unusual and interesting garnish for desserts, for example, and swizzle sticks coated in it can be offered with tea or coffee for an unusual twist on the traditional sugar bowl. The sugar may also be crystallized into cubes to form slow-dissolving and visually interesting sugar cubes. Some companies make the product available in a broken loose form for people who wish to sprinkle it onto scones, tarts, and other treats, and this loose form can also be added to ice cream and baked into various desserts for a textural surprise.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a DelightedCooking researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a DelightedCooking researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments

anon999616

Rock sugar and rock candy are not the same thing and not made the same way.

anon235069

Is this the same as pearl sugar? I looked for it for ages in Australia.

abiane

@doppler - I work for a candy store as well and have for a few months. Whenever my DM gives the go ahead I will usually order up a case of rock candy. It may be expensive (about $100 for 20 pounds I think), but it sells VERY quickly. It really is a novelty item and people really don't care about the price (at least where I work). Aside from that, I work in an area where people like to make confections that require decorations and use the rock candy for things like ice on a grooms cake.

ellaesans

@plaid - Most candy stores that sell by the pound have a set rate they sell at. Let's say $10.00 a pound or $2.50 per 1/4 pound for an example. The reason why things get so expensive so quickly is because of the weight of the candy. Gummi candy and Chocolate tend to be the heaviest and you will get less overall then say something like rainbow laces, licorice, or sour belts.

doppler

@WalrusTusk - I worked for a candy store like the one you are thinking of for a number of years and can tell you that the longer it takes to make a candy or the more time invested in making a candy, the more expensive it's going to be. Rock Candy takes an entire week (or 7 days) to start forming crystals and sometimes it can take way beyond that to get to the desired, sell-able size. This is the reason why you don't see many bulk candy stores (stores that sell by the pound) ordering up a bunch of rock candy all the time - it tends to be very expensive because of the investment of time when it comes to producing it.

plaid

@WalrusTusk - I am with you on that one! It's not just the rock candy, though, but things like chocolate and such. Especially in those stores where you buy candy by the pound.

WalrusTusk

A lot of high school or middle school students will often either opt to make rock candy for a science experiment at some point or actually have to make it as a requirement. I think it's fun and personally rock sugar crystals are fun to watch as they grow. I just don't understand why rock candy is so darn expensive in candy stores! Anyone?

Marvy

I'd like to know more Jaggery and "Chinese" or "Asian-Style". The latter comes in chunks but the crystals appear finer. Thank you.

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