How to Make Faux Gems From Crystals

Imitation Rubies, Amethyst, Emeralds, Diamonds, and Synthetic Quartz

Love gems but can't afford them? You can grow your own. Gemstones are aesthetically appealing minerals, usually crystals. Natural gemstones are mined, although it's possible to grow many of them in a lab.

Here's a look at synthetic or man-made gems you can grow as crystals. Some of the crystals are faux gems, meaning they resemble real gems but don't have the same chemical composition or properties. Others are synthetic gems, which have the exact same composition as natural gemstones, except they are grown rather than mined. Either way, these crystals are beautiful. 

Grow Faux Ruby Crystals

This is a crystal of potassium alum or potash alum
This is a crystal of potassium alum or potash alum. Food coloring was added to these crystals, which are clear when the alum is pure. Anne Helmenstine

Ruby and sapphire are two forms of the mineral corundum. It's possible to grow synthetic rubies and sapphires in a lab, but you need a high-temperature furnace and access to pure aluminum oxide (alumina) and chromium oxide.

On the other hand, it's quick, easy, and inexpensive to grow faux ruby crystals from potassium alum. This is the form of alum sometimes sold as natural deodorant crystals. Here's how to grow a fake (but pretty) ruby using this chemical:

Faux Ruby Materials

  • Potassium alum
  • Water
  • Food coloring


  1. Dissolve potassium alum in boiling water. Keep adding alum until no more will dissolve. This results in a saturated solution that promotes crystal growth.
  2. Add red food coloring to get a deep red color.
  3. Place the solution somewhere it won't get bumped or disturbed. Allow it to sit overnight. In the morning, use a spoon or your hands to remove the crystal.
  4. Place the crystal on a paper towel to dry.
  5. If desired, you can preserve the crystal to use. Keep in mind, it is not nearly as hard as corundum, so it is fragile.

Grow Faux Amethyst Crystals

This is a crystal of chrome alum, also known as chromium alum
This is a crystal of chrome alum, also known as chromium alum. The crystal displays the characteristic purple color and octahedral shape.

Ra'ike / Wikipedia Commons

Amethyst is a purple variety of quartz or silicon dioxide. If you're up for a challenge, I'll show you how to grow synthetic quartz yourself next, but first, let's grow a faux amethyst crystal from another type of alum—chrome alum. Chrome alum naturally produces deep violet crystals. If you mix it with potassium alum, you can lighten the color of the crystals to get any shade of purple, from pale lavender to deep violet.

Faux Amethyst Materials

  • Chrome alum
  • Water


  1. Dissolve chrome alum in boiling water until no more will dissolve. The solution will be deep blue-green, even though the crystals will be purple.
  2. You can simply let this solution sit for a few days and wait for crystals to develop, but to get a large, perfectly shaped crystal, it's best to grow a seed crystal.
  3. To grow a seed crystal, pour a small amount of the solution into a shallow saucer. Crystals will grow spontaneous as water evaporates out of the dish. Select the best crystal and place it in a clean container.
  4. Pour the rest of the growing solution over the crystal. The crystal will act as a nucleation site for more growth. It will be difficult to check on the progress of the crystal because the solution will be so dark, but if you shine a bright flashlight through the container, you should be able to see the size of the crystal.
  5. When you are satisfied with its growth, use a spoon to remove the crystal from the container.

Grow a Faux Emerald Crystal

This single crystal of ammonium phosphate grew overnight
This single crystal of ammonium phosphate grew overnight. The green-tinted crystal resembles an emerald. Ammonium phosphate is the chemical most commonly found in crystal growing kits. Anne Helmenstine

Emeralds are the green form of the mineral called beryl.

One easy way to grow a faux emerald crystal is to use monoammonium phosphate. This is the chemical found in most crystal kits that you can buy in stores because it's very safe and reliable. You can also find it sold as plant fertilizer (ammonium phosphate) and in some fire extinguishers.

Faux Emerald Crystal Materials

  • Monoammonium phosphate (ammonium phosphate)
  • Water
  • Green food coloring


  1. Stir 6 tablespoons of monoammonium phosphate into very hot water. The water does not need to be boiling hot.
  2. Add food coloring to get the desired color.
  3. To get large crystals, you want a slow rate of cooling. Usually, ​it's fine to simply let the mixture cool to room temperature and sit overnight. Don't refrigerate the mixture unless you want a mass of smaller crystals.
  4. When you are pleased with the crystal growth, pour off the solution and let the crystals dry.

Grow a Faux Diamond Crystal

A potassium alum crystal
A potassium alum crystal.

Christian Ude / Creative Commons License

Unless you have a chemical vapor deposition system or can apply incredible pressures to carbon, it's unlikely you can make your own diamonds.

However, you can grow beautiful clear crystals in several shapes using alum from your kitchen. These lovely crystals grow quickly.

Faux Diamond Materials

  • Alum
  • Water


  1. Mix 2-1/2 tablespoons of alum into 1/2 cup of very hot tap water or water heated in a coffee maker. You don't need boiling hot water.
  2. Let the solution slowly cool to room temperature. You should see small crystals forming in the container within a couple of hours.
  3. You can remove these crystals or select one or two of the best ones, remove them, and cover them with a fresh batch of the solution to get larger crystals.

Grow Synthetic Quartz Crystals

Crystals of quartz, the most abundant mineral in the Earth's crust
Crystals of quartz, the most abundant mineral in the Earth's crust. Ken Hammond, USDA

Quartz is crystalline silica or silicon dioxide. The pure crystal is clear, but impurities produce several colored gems, including amethyst, citrine, ametrine, and rose quartz.

It's possible to grow synthetic quartz at home. This material has the same chemical composition as natural quartz. What you need is silicic acid and a home pressure cooker. Silicic acid may be purchased or made by mixing powdered silica with water or by adding acid to ​sodium silicate solution (water glass). Once you have the starting materials, here's how to grow quartz.

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Your Citation
Helmenstine, Anne Marie, Ph.D. "How to Make Faux Gems From Crystals." ThoughtCo, Aug. 25, 2020, Helmenstine, Anne Marie, Ph.D. (2020, August 25). How to Make Faux Gems From Crystals. Retrieved from Helmenstine, Anne Marie, Ph.D. "How to Make Faux Gems From Crystals." ThoughtCo. (accessed March 31, 2023).