Fire Glass, Fire Stones or Lava Rock: A Design Guide

The media in your fire feature is the part people look at most, even when the fire is off. Fire glass catches and throws light, lava rock gives a quiet, matte base, and stones or logs bring a natural, almost campfire mood. The choice is mostly about style, but it starts with one practical rule: your burner's manual decides what media, and how much, can go in. This guide covers both, with pairing ideas for the concrete finishes we carry.

Three looks, three moods

Fire glass

Fire glass is the modern choice. Tumbled or faceted pieces sit in the burner pan and pick up the flame, so the whole surface glitters at night. Black and bronze glass read rich and restrained; clear and blue read bright and coastal; amber warms up a sand or terracotta body. In daylight, glass keeps a fire table looking finished even when it is off, which matters on a dining height table that people see all day.

Lava rock

Lava rock is matte, porous and dark, and it lets the flame do all the talking. On a charcoal or black concrete bowl it creates an almost monolithic look, with the fire as the only color. Tumbled lava, like Prism's gray tumbled lava rock, has softer edges and a lighter gray that suits pale finishes. Fire by Design's rolled lava stones sit somewhere in between, with rounded shapes that look almost like river pebbles.

Stones and logs

Decorative stones and log sets take the look in a more natural direction. American Fyre Designs offers creekstones, river rock "Fyre Stones," volcanic stones, branches and full log sets such as Back Country Oak and Desert Sage. On a gas fire table these create the mood of a campfire or a streambed, without the smoke or the ash. They suit rustic, ranch and lake house settings, and they soften the lines of a very crisp rectangular table.

Start with what your burner allows

Media is not just decoration. It sits over the burner and near the pilot, and every maker we carry has rules about it. Those rules differ, sometimes in opposite directions, so read your own manual before you buy anything.

Look at the pilot rules side by side. American Fyre Designs wants its pilot screen clear of media, while Fire by Design wants media in and around its pilot. Both are right for their own systems. This is the clearest reason never to copy a layering method from one brand to another, or from a video of a different fire pit.

What may already come with your feature

Before you add media to your cart, check what ships in the box. The makers we carry differ here too.

• Elementi's concrete fire tables include lava rock, and its porcelain tables include fire glass. The Sofia and Varna come with bronze glass; the Bianco and Carrara come with caribbean blue.
• Prism's Moderno manual lists 30 pounds of media included, and its Embarcadero 60 includes 150 pounds of tumbled lava rocks. Prism asks you to use only the amount provided.
• American Fyre Designs includes the lava granule base layer with its burners. For the decorative top layer, check your model's manual and listing for what is included and which of its media is approved.
• Slick Rock lets you choose glass, lava rock or no media when you order.

Our guide to what comes in the box goes through this brand by brand.

Pairing media with concrete finishes

The best pairings usually either match the body closely or contrast with it on purpose. A few starting points from the finishes we carry, all of which are our design suggestions rather than maker rules:

• Dark bodies (Slick Rock Onyx and Coal Gray, Prism Ebony, American Fyre Designs Black Lava): black glass or black lava rock for a tonal, architectural look; bronze glass if you want a warm glint.
• White and pale bodies (Slick Rock Great White, Prism Ultra, American Fyre Designs White Aspen): clear or blue glass for a crisp coastal feel; gray tumbled lava for something softer.
• Warm, earthy bodies (Slick Rock Adobe and Umber, Prism Cafe, American Fyre Designs Travertine and Cafe Blanco): amber glass, lava rock, or natural creekstones.
• Mid grays and naturals (Slick Rock Gray and Shale, Prism Pewter and Natural, American Fyre Designs Smoke): river rock and log sets for a natural setting; black glass for a modern one.

Elementi's own pairings on its porcelain tables follow the same logic: bronze glass on the black Sofia and Varna, caribbean blue on the white Bianco and Carrara. For more on finish colors, see our guide to choosing a concrete finish color.

How each looks after dark

Media changes completely at night. Glass is the most dramatic: each piece reflects the flame, and colored glass glows at the edges. Lava rock absorbs light, so the flame looks taller and the bowl reads as a dark silhouette, which is lovely on a pool edge where the water is doing the reflecting. Stones sit between the two, catching highlights on their rounded tops. Log sets are the most literal, and they look their best with a lower, lazier flame.

If the feature will be seen mostly from inside the house, glass tends to carry furthest. If it is the center of a seating group, where people look down into it, the texture of stones or lava rewards the closer view. Our guide to designing with firelight covers how to light the space around it.

Media near water and the pool

Pool bowls and fire and water bowls get splashed, rained on and misted by spillways. Wet media is the concern. Slick Rock warns that wet lava rock may pop and fly out of the bowl when heated, Elementi says to make sure lava rock is dry before lighting, and Prism says not to light with wet media. After rain or a pool party, give the media time to dry, and keep a cover on when the feature is off.

Glass rinses clean of leaves and pool debris with little effort. Whatever you choose, keep it clean and topped up to the level your manual sets, and no higher.

Choosing and buying media

Buy media from your feature's maker whenever the manual limits you to approved media, as American Fyre Designs does. For other brands, match the type and size the manual allows, and never add more than it calls for. Elementi notes that extra lava rock can cause sooting and a lower flame, which is the opposite of what anyone wants.

These are media options from the brands we carry. Match them to the maker of your fire feature.

You can also browse fire glass and the Fire by Design add-ons, which include lava rock and rolled lava stones.

Common questions

Can I mix fire glass and lava rock?

Only if your manual allows it. Some makers call for a base layer under the decorative media, and American Fyre Designs requires its lava granules to fill the burner area first. Others, like Prism, ask you to use only the media and amount provided. Check your own manual, and do not copy a layering method from a different brand or product.

How much fire glass or lava rock do I need?

Use the amount your manual specifies, not more. Prism asks owners to use only the amount provided, Fire by Design limits media to no more than 2 inches above the burner, and Elementi puts lava rock about 1 inch above the burner and warns that extra can cause sooting and a lower flame. Many features ship with their media, so check the box first.

Why did my lava rock pop when I lit the fire?

Moisture is the usual reason. Slick Rock warns that wet lava rock may pop and fly out of the bowl when heated, and Elementi and Prism both say media should be dry before lighting. After rain or heavy splashing, give it time to dry, keep a cover on when the feature is off, and take care the first time you light a new bowl.

Which fire glass color looks best with a concrete fire table?

Either match the body or contrast it on purpose. Black or bronze glass on a dark body reads calm and architectural. Clear or blue glass on a white body feels crisp and coastal. Amber glass or natural stones warm up sand and terracotta finishes. It is a style choice, so pick the media type your manual allows first, then choose the color.

Sources

1. American Fyre Designs, Fire Tables Installation and Owner's Manual L-H2-058, p. 15 (decorative media) and pp. 41 to 42
2. American Fyre Designs, Available Finishes and Textures
3. Fire by Design, FBD-0001 AWEIS Ignition System Instructions, REV 090826, p. 16 (media)
4. Prism Hardscapes, Embarcadero 60 Installation, Operation and Maintenance Manual, media section
5. Prism Hardscapes, Moderno Series Installation, Operation and Maintenance Manual, p. 10
6. Prism Hardscapes, Lombard Series Installation, Operation and Maintenance Manual, p. 14
7. Prism Hardscapes, 2025 Product Guide, p. 31 (finishes)
8. Elementi, OFG103NG Manhattan Fire Table Owner's Manual, pp. 8 to 9 and 13
9. Elementi, OFG309LP Andes Fire Table Owner's Manual, lava rock placement
10. Elementi, Service FAQ, lava rock quantity
11. Elementi, Sofia OFP103BB product page, and Carrara OFP121BW product page, included fire glass
12. Slick Rock Inc., Care and Maintenance, 2025
13. Slick Rock Concrete, Resources, Media Options and Colors