Diamond Rose Fault Line Cake – A 64th Anniversary Celebration

diamond buttercream rose fault line cake with isomalt diamonds and piped buttercream flowers

A few weeks ago, my grandparents celebrated their 64th wedding anniversary – yes, 64 years! What an accomplishment. To help them commemorate the occasion, I created this diamond rose fault line cake!

In case you’re not familiar, each year of marriage traditionally corresponds to a different gift or theme. For example, the 1st wedding anniversary gift theme is paper – stamps, stationery, a note in the newspaper, whatever the gift giver’s heart desires. The 15th-anniversary gift is crystal, the 20th is china, and, of course, the 50th-anniversary is gold.

However, to my initial dismay, the list seems to end at 60 years! So, after some further internet-sleuthing, I decided to take matters into my own hands – using just a little bit of mathematics. Don’t worry – it isn’t tough. You won’t need a calculator.

60+4=64, so I reasoned, “why not create a cake encompassing the 60th- and 4th-year anniversary gifts?” Thus, the diamond and rose fault line cake concept was born. Technically, the 4th-year anniversary gift is fruit or flowers, but a rose is a flower, so I think it counts. Of course, the 60th-year corresponding gift is a diamond.

Today, I’ll share with you a little more information on the materials and techniques I used to create this cake! That way, you can recreate this beauty on your own. Let’s get started!

diamond buttercream rose fault line cake with isomalt diamonds and piped buttercream flowers

Diamond Rose Fault Line Cake Tutorial

First, we’ll discuss the tools and materials you’ll need to replicate this cake design. Then, I’ll share some recipe ideas to get you started. I’ve even included links and references to some helpful videos, so be sure to read through the entire post! Most importantly, don’t forget to have fun!

Cake Tools & Materials List

Here are the basic tools you’ll need to bake your cake. I’ve included links (affiliate) for your easy reference and shopping. Keep in mind, depending on the specific recipe you choose, these may vary slightly. However, if you choose to create my triple chocolate cake linked below, this is exactly what you’ll need:

Now, to decorate the cake, you’ll need to gather the following items:

diamond buttercream rose fault line cake with isomalt diamonds and piped buttercream flowers

Diamond Rose Fault Line Cake Decorating Tips & Resources

Let’s get started decorating!

Step 1: Bake and Cool Cake, Then Prepare Buttercream

Depending on the recipe you choose, follow the instructions to bake your cake layers and prepare your buttercream. Make sure to let the cakes fully cool before attempting any decorating. This is the recipe I used – Triple Chocolate Oreo Crunch. It’s always a winner, and my family thoroughly enjoyed it this time, too!

Step 2: Stack and Crumb Coat Cake

After your cake layers have fully cooled, you can level off the domed tops, fill, and stack the layers together. Then, apply a thin layer of buttercream to the top and outside, scraping it down to smooth out the cake and lock in any fly-away crumbs.

Today I won’t go too much into the basics of crumb coating a cake, but if you want more instructions on this step, check out my blog post here. Not only do I describe each step thoroughly, but I also show a video demonstrating the process!

Chill the crumb-coated cake for about 10-15 minutes before working with it again. In the meantime, you can continue with steps 3 and 4.

Step 3: Create Isomalt Gems

CAUTION: Wear heat-proof gloves AT ALL TIMES when working with isomalt. Isomalt gets extremely hot and sticky and can cause second- and third-degree burns. Use extreme caution, work very slowly, and refrain from working with isomalt when children, pets, or other distractions are prevalent.

Place a few nibs of isomalt in the silicone measuring cup and place it in the microwave for 30-second intervals until it is fully melted. Then, extremely carefully and slowly, pour it into the cavities of the gem mold. Let the isomalt dry until it is hard and cool to the touch. Then, pop the gems out and set them aside for later. I leave them in a container with the lid not sealed so some air can get in. Otherwise, isomalt can get a bit sticky.

Step 4: Pipe and Freeze Buttercream Rose

Next, color a small amount of buttercream and, with it, pipe some roses. I created an extensive buttercream flower piping blog post here, with written instructions and a super thorough instruction video, too! Be sure to check it out if you’ve never piped flowers on a flower nail before.

For some other buttercream flower inspiration, check out these tutorials and videos:

Once you’ve finished piping your roses, pop them in the freezer. You don’t need many flowers for this cake, but you can always pipe more now and freeze them to use for another occasion! 🙂

diamond buttercream rose fault line cake with isomalt diamonds and piped buttercream flowers

Step 5: Add Your Base (Fault Line) Color

Color another small amount of buttercream in the shade that you’d like your fault line to appear. For mine, I made a soft mauve. Then, with an offset spatula, apply this buttercream around the sides near the center of the cake. You don’t have to cover the entire cake.

Then, using your bench scraper, smooth out this ring of buttercream as you would normally smooth the edges of the cake. However, don’t hold the scraper too tightly against the sides of the cake, otherwise, you’ll scrape it all off. The key is to use a soft, balanced force to smooth out the buttercream without removing it down to the crumb coat.

Step 6: Add Your Top (Final Coat) Color

For my final coat of buttercream, I used white to achieve an elegant, clean finish – but you can choose anything! Color your buttercream, and, with an offset spatula, apply the buttercream to the top of the cake, pushing it just over the edges. Smooth the buttercream down around the top few inches on the sides of the cake, but leave about 2/3’s of the cake without (for now).

Then, apply some of this same buttercream to the bottom few inches of the cake, leaving the middle empty.

Finally, use your bench scraper once again to smooth out this top coat of frosting. Again, use the proper balance to smooth the buttercream, without scraping into your fault line layer. Smooth this top layer out as many times as you need, adding more buttercream in order to refine the “rough” edge of the fault line.

Step 7: Gild The Fault Line

In a small bowl, mix a few drops of clear, food-grade alcohol with the gold luster dust to create a paint-like consistency. Then, paint it onto the “rough” under-edges of the top layer of buttercream.

diamond buttercream rose fault line cake with isomalt diamonds and piped buttercream flowers

Step 8: Add A Ganache Drip

Next, follow the instructions here to make a white chocolate ganache drip. Let the ganache cool to just above room temperature. In the meantime, chill the cake. This warm/cool combination is the key to the ganache dripping just enough – not too fast yet not too slow.

Once both temperatures are achieved, use a spoon to test one drop on the back of your cake. Adjust the ganache if necessary, cooling it down if the drip is too fast, or heating the ganache up if it doesn’t run at all. Then, carefully apply the drips all around the cake, finishing it off by pouring ganache in the center on top of the cake.

Step 9: Garnish With Roses and Diamonds

Using a tiny bit of leftover buttercream, stick your roses and diamonds carefully to your cake. Then, if you choose, apply a bit of silver luster dust to the diamonds with a paintbrush to give them an extra glimmer! The isomalt tends to have a slight tackiness to it, so you shouldn’t have to dilute it with any alcohol as you did the gold, earlier.

Finally, fit a piping bag with your leaf tip and add some finishing floral touches to the roses. You can find help piping leaves in my floral references above (see Step 4.)

diamond buttercream rose fault line cake with isomalt diamonds and piped buttercream flowers

Cake Notes:

This cake made as is (with my recipe) can sit at room temperature for two days. In fact, it should sit at room temperature, as the isomalt can become cloudy in the refrigerator. After that, place it in the fridge for 2-3 more days, or in the freezer for up to 3 months! Yum!

Yum! Enjoy Your Diamond Rose Fault Line Cake!

I hope you enjoy this cake as much as I did – it was very special to me, due to the occasion, of course. 🙂

Don’t forget to find me on Instagram so we can keep in touch, and be sure to tag me in any photos you post of your cake! I love to see your works of culinary art.

And, enter your email below to receive notification of my next blog post like this one. You don’t want to miss it!

Take care guys! Until next time…



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