The glowing green lagoon effect produced by the Sukabumi stone can be attributed to the stone’s natural formation. However, search online for information about Sukabumi stone and you’ll find many misconceptions about its origins and geological makeup, even from companies that sell it.
Some reports state it’s a sedimentary rock, formed from minerals and fragments compressed and hardened over time; others claim it’s metamorphic, transformed under the stress of heat and pressure deep within the Earth. Newsflash: neither is true. Despite online info, Sukabumi is also not a type of sandstone, quartzite, green marble or serpentine.
Allow us to set the record straight on how this remarkable stone is formed and what gives it its glowing properties when submerged underwater as a pool tile.
To get down to the bottom of Sukabumi once and for all, we at Island Stone & Tile provided Sukabumi samples to the Natural Stone Institute (NSI) for a petrographic analysis that could definitively identify its minerals, texture, structure, and how it formed. The results are important for understanding properties such as a stone’s strength, durability, texture, fabric, and how it may react to water and the elements. This information can help ensure we deliver the highest quality and most reliable materials to our customers, as well as help them maintain the stone over time.
Sukabumi Stone collection product variations.
The Anatomy of Sukabumi
The NSI analysis confirmed Sukabumi is a type of extrusive igneous stone, which means it forms when molten rock cools relatively quickly on or near the Earth’s surface. The stone is native to Indonesia and is also sometimes called Pedra Hijau Verde, Indonesia Green Stone, or Bali Stone,
Sukabumi is made mostly of feldspar — one of the most common minerals on Earth — along with green volcanic glass and small amounts of darker minerals such as pyroxene and biotite. It also contains occasional larger crystals of quartz and feldspar, along with tiny pieces of volcanic rock that were trapped inside the material as it formed.
One of the stone’s most distinctive features is its flowing, layered appearance. This texture formed while the lava was still moving before it fully hardened, causing minerals and glassy materials to align in parallel patterns.
The NSI report also notes the presence of small pores within the stone. Some of these empty spaces developed when certain mineral crystals slowly dissolved over time. In a few areas, these voids became partially filled with clay minerals that formed naturally within the rock. If you really want to tile-geek out, the test results from our full analysis can be found in the Sukabumi Select Spec Sheet.
Green volcanic glass gives Sukabumi Stone its lagoon-like color.
Green Light, Go!
Seen up close, the green volcanic glass in Sukabumi can look like fragments of Kryptonite, and the impact of this colorful aspect gives the stone a lagoon-like essence. It emits a spectrum of lagoon-like hues, from teal to turquoise to green and everything in between.
“Outside of the water, Sukabumi may have a flat, basic color, but there’s some sort of magic that happens once it’s submerged,” said Cathy Aroz, Island Stone & Tile’s lead designer of new product development and marketing. “When there’s a layer of water on top, and light travels through and hits the surface, all of a sudden the reflection of the stone becomes almost like a jewel tone.”
This is the result of the same phenomenon that makes our sky blue: the scattering of light. When light hits a material like a stone surface, which is not uniform, its rays will bounce around in different directions. Some of the light reflects back immediately, some penetrates deeper into the stone, and some scatters internally as it hits the stone’s features, like Sukambumi’s green glass and pores.
Stones with many tiny air spaces or rough internal textures tend to scatter more light. Sukabumi is classified as a trachyte, which comes from the ancient Greek word “trachys,” meaning rough or bumpy. The stone’s porous makeup is part of what creates the glowing, green hue it projects under a layer of water.
When dry,the stone’s pores are filled with air, which makes the surface appear lighter and less saturated in color. But when submerged, water fills its pores and more light is absorbed before reflecting back out. As a result, the stone appears darker, richer, and more vibrant in color.
This is the same effect you see when beach rocks suddenly look vivid after waves wash over them. In the case of Sukabumi, the wet stone darkens and the green highlights become more pronounced as it reflects through the water.
Sealed Sukabumi Stone enhancing the richness and variation of the green mosaic tiles.
Seal the Deal
Whether you are a fan of Sukabumi’s dry look or you prefer the luminescent green so popular across Southeast Asia, we recommend sealing the tile before you fill your pool with water. If you want the color to shift, we recommend using an enhancing sealer, which should mimic the stone’s appearance when wet. If you prefer the stone to appear more like it does when dry, apply a penetrating sealer (sometimes called a “natural look sealer”) to prevent water from filling its pores and limit the color change when exposed to moisture.
“If you want that color change, then you should consider using an enhancing sealer as opposed to a natural look sealer,” Island Stone & Tile Director of Technical Services David Fatula said. “The perception of color is entirely subjective; some people like the light green, mint chocolate chip tone, while others prefer the deeper green that appears when wet – it’s all subjective. But what isn't subjective for me is that it should be sealed.”
Combined with regular cleaning, either sealer you choose will help prevent staining and slow weathering from long-term exposure to the sun. Sealing the stone promptly after installation can also stop the small deposits of iron in the stone from turning into rusty spots.
“In other markets, they don't seal Sukubumi because they don't mind seeing a little bit of that rust on the surface,” Fatula said. “In the U.S. market, we have a different expectation with our natural stone, and generally, people don't want to see that.”
See for Yourself
If you’d like to view a sample of Sukabumi, contact us today or visit our Dealer Locator web app to find a partner in your area. These showrooms frequently carry spray bottles to show customers what the stone looks like wet vs. dry.
