What Are the Different Types of Curly Koa?

Quick Summary — What Is Curly Koa?

Curly koa is one of the most visually distinctive forms of Hawaiian koa wood, prized for a remarkable figure that can appear to ripple, shimmer, or move as light travels across its surface. But curly koa is not a separate species of koa. Rather, “curl” describes a type of figure created by variations in the orientation of the wood fibers.

Not all curl looks alike. It can be fine and tightly spaced, broad and sweeping, highly regular, irregular and rolling, intensely chatoyant, or a complex combination of several characteristics.

The most dramatic curly koa can have an almost three-dimensional appearance. Turn the wood slightly and areas that looked dark become bright, while other areas seem to disappear and reappear. This interaction with light—known as chatoyance—is one reason exceptional curly koa is so highly prized.

Understanding curly koa therefore requires looking beyond a simple label. Its beauty comes from the width, depth, spacing, consistency, direction, color, and optical intensity of its figure—and from the fact that nature rarely produces two pieces exactly alike.

What Is Koa, and Why Is It So Special?

Koa, botanically known as Acacia koa, is native to the Hawaiian Islands and is one of Hawaiʻi’s most celebrated woods.

Its beauty begins with color. Koa can range from pale golden and honey tones to amber, reddish brown, rich chocolate, and combinations of these colors within a single piece. Its grain may be relatively straight or dramatically sweeping and figured.

But koa’s importance in Hawaiʻi goes far beyond appearance.

For generations, Native Hawaiians used koa for important functional objects, including waʻa, or canoes, as well as surfboards, bowls, containers, tools, and other objects. Its combination of strength, workability, and beauty made it an extraordinarily useful natural resource.

Over time, koa also became closely associated with Hawaiian furniture, musical instruments, decorative objects, and fine woodworking. Today, an exceptional piece of koa can immediately evoke Hawaiʻi in a way few other materials can.

That connection between place, history, nature, and craftsmanship helps explain why koa is prized well beyond the Hawaiian Islands. Woodworkers, musicians, furniture collectors, designers, and people who simply appreciate extraordinary natural materials seek it out around the world.

And within the world of koa, some of the most remarkable wood is curly koa.

What Does “Curly” Actually Mean in Koa?

To understand curly koa, it helps to distinguish several terms that are sometimes used interchangeably.

Grain generally describes the direction and arrangement of the wood fibers.

Figure describes the visible patterns created by the structure of the wood, the direction of those fibers, and the way the log or board has been cut.

Curl is a form of figure in which variations in fiber orientation create repeating bands or areas that reflect light differently.

And then there is chatoyance.

Chatoyance is the optical effect that makes figured wood appear to change as either the wood, the light source, or the viewer moves. The word is also used to describe certain gemstones with dramatic light-reflecting characteristics.

This distinction is important because curl is not simply a pattern printed onto the surface of koa.

Color is something you see in the wood. With exceptional curl, the figure can appear to move across the wood.

Stand on one side of a highly figured koa table and one band may look dark while the adjoining band appears golden. Walk to the opposite side and the relationship can reverse.

That is why photographs, no matter how good, can have difficulty capturing the full beauty of exceptional curly koa. It is a material best experienced in changing light and from multiple angles.

What Causes Curl in Koa?

Wood fibers in a tree do not necessarily grow in perfectly straight, uniform lines.

When the orientation of those fibers changes or undulates within the tree, a board cut through that structure can expose alternating areas of differently oriented fibers. Those areas interact with light differently, producing the characteristic bands, ripples, and flashes associated with curl.

What causes those variations in the first place is more complicated.  Several factors may contribute to figured growth in trees, including:

• Genetics
• The tree’s natural growth patterns
• Mechanical stresses during growth
• Trunk and branch geometry
• Environmental conditions
• Age and development
• The particular location of the wood within the tree

It is tempting to attribute exceptional curly koa to one particular growing condition—elevation, rainfall, wind, soil, age, or location—but nature is rarely that simple.

Is Curly Koa Genetic or Environmental?

The most accurate answer is that it should not be treated as a simple choice between genetics and environment.

A tree’s genetics influence how it grows. At the same time, a living tree responds continuously to its environment and to physical forces over decades of growth.

Wind, gravity, branching, uneven loading, changing growing conditions, injury, and other stresses can influence how wood develops. The interaction between inherited characteristics and a tree’s individual growing history can therefore be complex.

This also helps explain one of the fascinating aspects of koa: the extraordinary figure inside a tree is not always obvious from the outside.

An experienced person may recognize characteristics that suggest interesting wood, but it is generally not possible simply to look at a standing koa tree and know precisely what figure will eventually be revealed inside.

The true character of the wood becomes apparent when it is milled and individual boards are examined.

Six Ways Curly Koa Can Differ

There is no universally accepted botanical system dividing curly koa into six official categories. Instead, craftspeople and woodworkers describe figure according to characteristics they can see in individual boards.

These descriptions are useful because they help explain just how different one piece of curly koa can be from another.

1. Fine or Tight Curl

Fine or tight curl consists of relatively narrow, closely spaced bands of figure.

Instead of broad waves extending across the wood, the figure may repeat frequently over a relatively small distance. The result can be an intricate visual texture, especially when the curl is strong and consistent.

Tight curl can produce considerable visual activity. As the viewing angle changes, numerous small bands may brighten and darken in succession.

However, tightness alone does not determine quality. A tightly curled board with relatively weak figure may be less visually dramatic than a wider curl displaying exceptional depth and chatoyance. Spacing is therefore only one characteristic used when evaluating figured koa.

2. Broad or Wide Curl

Broad curl occurs when the visual bands are spaced farther apart.

Instead of numerous narrow ripples, the board may display larger areas of light and dark that seem to sweep across its surface.

This type of figure can be especially impressive on large pieces of furniture because there is enough surface area for the scale of the figure to reveal itself.

A broad, highly figured piece of koa across a dining table, cabinet front, desk, or headboard can produce large flashes of reflected light as someone moves around it.

Neither tight nor broad curl is inherently superior. They simply create different visual experiences.

3. Uniform or Consistent Curl

Some exceptional boards display curl with remarkable consistency. The spacing, strength, and direction of the figure may continue across much of the board, creating an almost rhythmic appearance.

Consistency becomes particularly important in furniture making.

Finding one beautiful board is one challenge. Finding several boards with complementary color, figure, and intensity for a large piece of furniture can be considerably more difficult.

An experienced furniture maker therefore evaluates not only the beauty of an individual board but also how that board relates visually to every other piece of wood surrounding it.

4. Irregular or Rolling Curl

Nature does not always produce orderly patterns.

In some koa, curl changes in width, direction, spacing, or intensity as it travels through the board. The figure may appear to roll, bend, sweep, or undulate rather than repeat at predictable intervals.

This irregularity should not automatically be considered a flaw.  In fact, complex and unpredictable figure can create some of koa’s most interesting visual effects. One section of a board may display strong rippling while another transitions into sweeping grain or a broader area of figure.

The result can feel remarkably organic—which is exactly what it is. The pattern records the growth of an individual tree rather than a design imposed upon the wood.

5. Deep, Highly Chatoyant Curl

Some curly koa becomes especially prized because of the intensity of its chatoyance.

When light strikes highly figured koa, differences in fiber orientation cause adjoining areas to reflect light differently. As the viewer moves, those reflections change.

A bright golden band may become darker. A previously subdued area may suddenly flash with light. The figure can seem to shift underneath the surface even though the wood itself is perfectly smooth.  This creates an extraordinary impression of depth.

The comparison with gemstones is particularly useful here. Chatoyant gemstones can display a band or concentration of reflected light that changes as the stone moves. Highly figured koa can produce a related visual experience.

The effect is not paint, stain, or an artificial surface treatment. It originates in the structure of the wood itself.

A quality finish can reveal and enhance the effect, but it cannot manufacture true curl that wasn’t present in the wood to begin with.

6. Complex or Mixed Figure

Perhaps the most important category is the one that refuses to fit neatly into a category.

A single koa board can combine several visual characteristics.

It might contain tight curl in one area and broader curl in another. Curl may intersect with sweeping grain. Color may transition from golden amber to reddish brown. Figure may become stronger toward one portion of the board and more subtle elsewhere.

This is why descriptions such as “tight curl” or “broad curl” only tell part of the story. Fine koa is produced by nature, not according to a grading chart.

Ultimately, the character of an exceptional board comes from the interaction of figure, color, grain, scale, consistency, contrast, and chatoyance.

The combination may be impossible to reproduce exactly in another piece of wood.

 

 

How Cutting and Finishing Reveal Curly Koa

The figure that ultimately appears in a koa board depends partly on how the wood is cut.

A saw intersects the internal structure of a log at a particular angle. Change that angle and the visual presentation of the grain and figure can change as well.

This means the craftsperson plays an important role in revealing what nature has created.

Board orientation, cutting decisions, surface preparation, sanding, and finishing can all influence how clearly the figure can be appreciated.

Lighting matters too.

Highly figured koa may look relatively restrained under flat, diffuse illumination and dramatically alive when light strikes it from another direction.

Finishing deserves an important clarification: a finish does not create genuine curl.

Instead, a properly prepared and finished surface can make the existing figure easier to see by allowing light to interact more effectively with the wood.

For furniture makers experienced with koa, board selection is therefore part of the design process. A particularly dramatic board may be reserved for a tabletop, cabinet front, headboard, or another prominent area where its figure can be fully appreciated.

Why Highly Curly Koa Is So Valuable

Not every koa tree contains highly figured wood, and not every figured section produces large, usable boards with exceptional color and consistency.

That scarcity is one reason highly curly koa can command a significant premium.

Value may depend on numerous characteristics, including:

• Strength and depth of figure
• Consistency of the curl
• Chatoyance
• Color
• Board size and thickness
• Defects or imperfections
• Ability to match multiple boards
• Provenance
• Quality of craftsmanship
• Overall visual character

A small piece of dramatically figured koa is one thing. Finding a large board—or a group of compatible boards—with exceptional figure is another matter entirely.

This becomes particularly important in fine furniture.

For decades, Martin & MacArthur has worked extensively with Hawaiian koa, giving its craftspeople experience not simply in identifying curly wood but in selecting, matching, orienting, and finishing boards so their natural figure works together within a finished piece.

That distinction matters. Extraordinary material does not automatically produce extraordinary furniture. The maker must understand what the wood is doing and allow its natural character to become part of the design.

Conclusion — No Two Pieces of Curly Koa Are Exactly Alike

There is no single appearance that defines all curly koa.

Some curl is narrow and tightly spaced. Some is broad and sweeping. Some repeats with remarkable consistency, while other figure rolls unpredictably through the board. And in the most dramatic examples, strong chatoyance can make the surface seem almost three-dimensional.

Understanding curly koa therefore means looking at several characteristics together: spacing, width, regularity, orientation, intensity, chatoyance, color, and cut.  That variability is part of what makes the wood extraordinary.

The finest curly koa rewards movement. Look at it from one direction and you see one pattern of light and color. Change your position and another emerges.

You don’t simply look at exceptional curly koa once.  You experience it as the light changes.

That combination of natural beauty, rarity, Hawaiian heritage, and individual character helps explain why exceptional koa has fascinated generations of craftspeople—and why it continues to be prized by collectors and admirers throughout Hawaiʻi and around the world.

Frequently Asked Questions About Curly Koa

1. What exactly is curly koa?

Curly koa is koa wood displaying a distinctive type of figure created by variations in the orientation of its wood fibers. It is not a separate species of koa. The term “curly” describes the visual and optical character of the wood.

2. What causes koa wood to become curly?

Curl develops when wood fibers do not run in completely uniform, straight directions. Variations in fiber orientation can produce alternating areas that reflect light differently when the wood is cut. Genetics, growth patterns, mechanical stresses, tree structure, and environmental conditions may all contribute to how figure develops.

3. Is curly koa genetic?

Genetics may influence a tree’s tendency to develop particular growth characteristics, but curl should not automatically be attributed to genetics alone. The structure of wood develops over many years as a tree responds to its individual growth conditions and mechanical stresses. The relationship between genetics and environment is complex.

4. Can you tell whether a koa tree contains curly wood before it is cut?

Not with complete reliability. External characteristics may sometimes suggest unusual growth, but the precise quality, location, and intensity of figure inside a tree generally cannot be known simply by looking at its exterior. The character of the figure becomes much clearer when the wood is milled into boards.

5. What is the difference between tight curl and broad curl?

Tight curl generally has narrow, closely spaced bands, while broad curl has wider spacing and larger areas of changing reflection. Neither is automatically better. The beauty and value of a particular board also depend on intensity, consistency, color, chatoyance, size, and overall visual character.

6. What is chatoyance in curly koa?

Chatoyance is an optical effect in which areas of the wood appear to brighten, darken, or move as the viewing angle or lighting changes. The term is also associated with certain gemstones. In highly figured koa, chatoyance can create a striking impression of depth and movement.

7. Does curly koa cost more than regular koa?

Highly figured curly koa generally commands a premium because exceptional figure is comparatively scarce. Price can also depend on the intensity and consistency of the curl, board dimensions, color, defects, provenance, ability to match boards, and the craftsmanship of the finished object.

8. What should I look for when buying curly koa furniture?

Look at the furniture from several angles rather than judging it from a single viewpoint. Strong curly koa should reveal changing light, figure, and depth as you move around it. Also consider the quality of the craftsmanship, how well adjoining boards have been selected and matched, the color and consistency of the wood, the quality of the finish, and the provenance of the koa.

Ultimately, the best piece of curly koa furniture is not necessarily the one with the most obvious pattern. It is the one in which exceptional wood, thoughtful board selection, skilled craftsmanship, and beautiful design come together as a whole.