One kind of video that has been constantly popping up my social media feed are these ASMR videos of Japanese crystal candy from a brand called Silky Gem. They are so beautiful and so crunchy, I couldn’t resist trying to make them myself.
Fair warning though — this recipe requires a bit of patience since the candy needs at least a week to dry out and develop that signature crunchy shell.
But if you’ve got little ones at home, this is a fun project to do together. They’ll love shaping and coloring their own edible crystals.
Also keep in mind, these candies are incredibly sweet, but there are a few ways to tone down or mask the sweetness with some choice ingredients.
What is Kohakutou?
Kohakutou is a traditional Japanese candy that looks like gemstones or crystals.
The basic version requires just three ingredients: water, agar agar powder, and sugar. However, you can add different flavors and colors to make it awesome.
The mixture is heated to activate the agar agar, a natural gelling agent made from red algae (a type of seaweed). This sets the mixture. Once firm, it’s cut into small pieces to resemble crystals then set out to cure.
As it dries at room temperature over several days to a week, the exterior develops a crunchy, crystallized sugar coating, while the inside stays soft and jelly-like.
What You Will Need
To make kohakutou, gather the following ingredients:
- Agar agar powder: A plant-based alternative to gelatin that gives the candy its unique texture and makes it naturally vegan. I’m using the white and blue Telephone brand agar agar powder from Thailand.
- Water or other flavorings: To make the candy base, you can use water, juice or tea. If you’re using something other than water, I recommend sticking to something sour or bitter because it’s already going to be really sweet. I’m adding passion fruit pulp, which is super sour and also gives the jelly a beautiful yellow color. Tamarind is another great sour option. Matcha is an excellent choice for something slightly bitter and it also adds a lovely green color to the jelly. Have fun and be creative!
- Sugar: Granulated sugar is essential for forming the crystallized outer coating.
- Food colorings, gels or extracts: This is optional for the ripple color effect. I’m using pandan extract for a beautiful green color with a wonderful pandan aroma. Another Asian food coloring alternative is ube extract for a beautiful purple color.
How to Make Kohakutou
Step 1: Make the Jelly Mixture
In a small saucepan, combine water and passion fruit pulp (or your preferred liquid), agar agar powder, and granulated sugar. Mix well.
Heat the mixture until it comes to a boil, about 6 minutes. Reduce the heat and let it simmer for about 4 more minutes, or until the liquid clings to the spoon when lifted. Be careful of overflow. Reduce heat if needed.
Step 2: Transfer to a Mold & Color
Pour the mixture into a flat, heatproof container. Aim for a depth of at least 1 inch when poured.
The poured liquid should be thick enough that any food coloring, gel, or extract you add will hold rather than spreading out. If the mixture is too watery let it sit for a minute for the agar agar to thicken the mixture before adding color.
Use a toothpick to dip into the food coloring and swirl it into the jelly mixture to create streaks and swirls.
Step 3: Set the Jelly
Transfer the mold to the fridge and let it set into a firm jelly (about one hour).
Step 4: Shape the Candy (The Fun Part)
Once firm, run a knife along the edges to loosen then lift the jelly out.
Tear the jelly into pieces by hand to create natural, jagged edges that resemble shards of glass. You can also use a knife to cut irregular, crystal-like shapes.
You can take any leftover small pieces and press them onto the larger pieces for a decorative top.
Step 5: Dry & Crystallize (The Long Wait)
Place the shaped pieces on parchment paper and leave them to dry at room temperature for about one week. Cover loosely with tented parchment paper to keep dust off.
The outer shell will harden, creating the signature crunchy shell but the interior will remain soft. Once fully dried, store the candy in an airtight container at room temperature for up to one month.
FAQs
Can I use gelatin instead of agar agar?
Agar agar is key to achieving the unique texture of Kohakutou. Gelatin won’t produce the same results.
How long does Kohakutou last?
Once dried, it can last up to a month in an airtight container. Keep it in a cool, dry place.
Why didn’t my candy crystallize?
Ensure the candy pieces are exposed to air evenly during the drying process. Humid or cold environments can delay or prevent crystallization. Turn occasionally for best results.
Kohakutou (Japanese Crystal Candy)
- Total Time: 1 hour 10 minutes
- Yield: 15–20 crystals 1x
Description
A stunning Japanese crystal candy with a crunchy shell and jelly-like center. It’s fun to make, kid-friendly, naturally vegan, and perfect for anyone who loves edible art projects.
Ingredients
- 1 cup water
- 1 tablespoon passion fruit pulp or matcha powder (skip if using juice for water)
- 1 1/2 cups granulated sugar
- 1 tablespoon agar agar powder
- Pandan extract (or your favorite food coloring/extract)
Instructions
- Make the Jelly Mixture: In a small saucepan, combine water and passion fruit pulp (or your preferred liquid), agar agar powder, and granulated sugar. Mix well. Heat over medium-low until the mixture comes to a boil, about 6 minutes. Reduce the heat and let it simmer for about 4 more minutes, or until the liquid clings to the spoon when lifted.
- Transfer to a Mold & Color: Pour the mixture into a flat, heatproof container. Aim for a depth of at least 1 inch. The liquid should be thick enough that any food coloring, gel, or extract you add will hold rather than spreading out. If the mixture is too watery let it sit for a minute for the agar agar to thicken it before adding color. Use a toothpick to dip into the food coloring and swirl it into the jelly to create streaks and swirls.
- Set the Jelly: Transfer the mold to the fridge and let the jelly set (about one hour).
- Shape the Candy: Once the jelly is firm, run a knife along the edges to loosen then lift the jelly out. Tear the jelly into pieces by hand to create natural, jagged edges that resemble shards of glass. You can also use a knife to cut irregular, crystal-like shapes. Take any leftover small pieces and press them onto the larger pieces.
- Dry & Crystallize: Place the shaped pieces on parchment paper and leave them to dry at room temperature for about one week. Cover loosely with tented parchment paper to keep dust off. The outer shell will harden, creating the signature crunchy shell and the interior will be remain soft. Once fully dried, store the candy in an airtight container at room temperature for up to one month.
- Prep Time: 1 hour
- Cook Time: 10 minutes
- Category: dessert
- Method: stove top
- Cuisine: Asian, Japanese
