Everything You Need to Know About Diamond Stitching Awls in Leathercraft

Everything You Need to Know About Diamond Stitching Awls in Leathercraft

If you've been bitten by the leatherworking bug — and it's a hobby that bites hard — you'll quickly discover that the quality of your stitching depends as much on preparation as it does on the needle and thread. At the heart of that preparation sits a deceptively simple tool: the diamond stitching awl.

What Is a Diamond Stitching Awl?

A diamond stitching awl (also called a diamond awl, stitching awl or diamond pricking awl) is a hand tool used to pierce holes through leather in preparation for hand-stitching. Unlike a round awl — which forces fibres apart — a diamond awl's blade is ground to a four-sided, lozenge-shaped cross-section. This geometry does something rather clever: it creates clean, elongated slots that align with the direction of your stitch, allowing the thread to lie flat and snugly within the leather.

The result is the hallmark of quality hand-stitching: a herringbone pattern of slightly angled, even holes that produces stitching which is not only stronger than machine-sewn work, but genuinely beautiful.

Diamond Awl vs. Pricking Iron: What's the Difference?

New leatherworkers are often confused by the relationship between diamond awls and pricking irons. They are complementary tools, not interchangeable ones.

A pricking iron (or stitching chisel) is struck with a mallet along the surface of the leather to mark a row of evenly-spaced holes. It establishes your stitch spacing and, in lighter leathers, may pierce all the way through. A diamond stitching awl is then used to open each marked hole fully, or to pierce thick leathers where a pricking iron alone won't reach the reverse side.

On thicker leathers (4mm and above), always follow your pricking iron with a diamond awl. Trying to force thread through a partially-pierced hole is one of the most common causes of broken threads and uneven stitching.

Some craftspeople skip the pricking iron entirely on soft or thin leathers, using the diamond awl freehand with a stitching groove as their guide. With practice, this produces beautifully even results — but for beginners, the two-step method is far more forgiving.

The Anatomy of a Good Diamond Awl

The Blade

Blade quality is everything. You want high-carbon steel that will take and hold a keen edge. The blade should be properly angled — typically between 45° and 60° — so that holes open at the correct angle to produce a diagonal, interlocked stitch. A blade ground too steeply will make vertical holes; too shallowly and the tool becomes difficult to control. The faces of a quality blade will have a polished, mirror-like finish to reduce friction as it passes through the leather.

The Handle

Because you will be pushing, twisting, and manoeuvring the awl repeatedly in a single session, the handle deserves real attention. Hardwood handles — oak, rosewood, and walnut being popular choices — provide enough grip without being harsh on the palm. Well-turned handles with a slight waist allow for comfortable rotation. Some craftspeople prefer a rounded mushroom cap at the butt end, which allows the heel of the palm to apply downward pressure without discomfort.

Blade Sizes

Diamond awls are available in several widths to match different thread gauges. A narrower blade is used with fine waxed thread for delicate goods like cardholders and watch straps, whilst a wider blade suits the heavier thread used on belts, holsters, and saddlery work. Using the wrong blade size for your thread is a common mistake: too narrow and the thread won't seat properly; too wide and you'll have unsightly gaps around the stitch.

Choosing the Right Awl for Your Project

These are guidelines rather than rules — personal preference and stitch spacing will ultimately determine your ideal blade. Many experienced leatherworkers keep two or three different awl sizes on the bench and reach for each as the project demands.

How to Use a Diamond Stitching Awl

1. Mark Your Stitch Line

Begin by running a stitching groover along the edge of your leather piece to cut a shallow channel. This recesses the stitching below the surface, protecting it from abrasion and giving the finished piece a professional, sharp appearance. Follow the groove with a pair of wing dividers or a stitching spacer to mark your hole positions.

2. Use a Pricking Iron to Set Spacing

Working on a firm surface (a granite offcut or stitching pony), use your pricking iron and a mallet to mark the hole spacing along the groove. The iron's tines should penetrate the surface without necessarily going all the way through on thicker leathers.

3. Pierce With the Diamond Awl

Hold the awl so its blade faces align with your stitch direction — the longer axis of the diamond running parallel to the edge. Push firmly through the marked hole, using a slight twisting motion if needed. The blade should emerge cleanly on the reverse side. Maintain a consistent angle throughout; a wobbly angle is immediately visible in the finished stitching.

4. Stitch Using the Saddle Stitch Method

With your holes pierced, thread two needles on a single length of waxed thread and work the saddle stitch: both needles pass through each hole in opposite directions, creating a locked, self-reinforcing stitch that will outlast the leather itself.

Pierce only a few holes ahead of your stitching position rather than all at once. On thick leathers, holes can partially close as the fibres spring back, making re-piercing necessary if you get too far ahead.

Maintaining Your Diamond Awl

A sharp awl is a pleasure to use; a dull one is a hazard and a source of frustration. Keep your blade in good order by stropping it regularly on a leather strop charged with green polishing compound — the same compound you use for finishing edges works perfectly well. You are aiming for a mirror polish on all four faces of the blade.

Between uses, protect the blade from moisture and knocks by storing it in a purpose-made tool roll or at least slipping a small cork over the tip. A rusted or chipped awl blade cannot be properly sharpened back to usefulness; it is far better to prevent the problem in the first place.

If you do need to reshape a blade that has been damaged or incorrectly ground, a fine India stone followed by progressively finer wet-and-dry paper (up to 2000 grit) and then the strop will bring it back. It is a meditative process — and rather satisfying.

Common Mistakes to Avoid

Misaligning the Blade

The diamond awl only produces correct stitch holes when the blade is held at a consistent angle. If you rotate the awl between holes, or if your grip shifts during a stroke, the resulting holes will be oriented differently, and the stitching will look uneven. Before beginning a seam, take a moment to establish your grip and mark the blade's correct orientation clearly in your mind.

Using Too Much Force

A sharp diamond awl should require almost no force to penetrate even firm vegetable-tanned leather. If you are pushing hard, either the blade needs sharpening or you are working too quickly. Excessive force causes tearing rather than clean cutting, and tears are very difficult to conceal in finished work.

Skipping the Stitching Groove

It is tempting to go straight to piercing, especially on small projects, but running a groover first makes a meaningful difference to the final appearance. Stitching that sits flush in a groove is protected and visually sharp; stitching on a bare surface sits proud and looks comparatively amateurish.

Purchasing a Poor-Quality Awl

Budget diamond awls are a false economy. An awl with a poorly-ground blade will never sharpen properly, and a handle that twists in the chuck after a few sessions will undermine your consistency. It is worth investing in a quality tool from a specialist supplier — one that, treated well, will last decades.

A Word on Quality

Leatherwork is one of those crafts where the tools you use have a direct and visible effect on the quality of your output. This is never more true than with the diamond stitching awl, which influences the regularity of your stitching, the cleanliness of your holes, and ultimately whether the seam you spend an hour saddle-stitching is a source of pride or disappointment.

Buy tools from suppliers who understand the craft — who stock awls ground by people who use them, and who can advise on the right blade size for the work you're doing. The difference between a correctly-specified quality awl and a generic substitute is not subtle; it is immediately apparent the first time the blade slides through veg-tan without resistance, leaving a clean, angled slot ready for the needle.

Ready to start stitching? Browse the full range of diamond stitching awls at British Leather Supplies — selected for the serious leatherworker.