2026.09.18 2026.09.19

Japanese Decoden & Parts Decoration: A Complete Guide to Types and How to Choose the Right Craft Parts

yassy

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Hello! This is Yassy from Crafters! (・∀・)

Parts decoration—often known in Japan as "Decoden"—is a wonderful craft where you can decorate everyday accessories and smartphone cases with your favorite small embellishments. It is a fantastic way to express your personal style. While it is easy to get started, browsing craft stores or online shops can be overwhelming because of the vast array of available parts, leaving many crafters wondering where to begin.

Selecting the right parts is a crucial step that directly impacts not only the appearance and overall finish of your project, but also its durability. If you pick parts haphazardly, your item might lack sparkle, or the embellishments may end up popping off during daily use.

In this guide, I will explain the most common types of parts used in Japanese parts decoration, the differences in back shapes, how to read sizing standards, and key tips for selecting parts that will dramatically elevate the quality of your craft work. Let's master the basics so you can create the shimmering decorated project of your dreams!

Types and Features of Typical Parts Used in Parts Decoration
How Back Shapes Affect Your Craft: Shapes and Precautions
Understanding Sizes: Navigating Sizes Without Confusion
- Rhinestone Sizing Guide: Understanding "ss"
- Millimeter (mm) Sizing for Resin Parts and Pearls
5 Key Points for Choosing Parts Without Failure
Common Beginner Mistakes and How to Fix Them
How I Would Combine Parts for High-Impact Designs
- For Smartphone Cases: Mixing Textures for Depth
- For Compact Mirrors and Hair Clips: Monochromatic Gradients
Summary

Types and Features of Typical Parts Used in Parts Decoration

In the world of parts decoration, you will find a wide variety of materials, ranging from shimmering stones to cute three-dimensional charms. First, let's take a look at the representative types of parts and their unique characteristics.

Rhinestones: The Timeless Classic for Maximum Sparkle

Rhinestones are the most commonly used element in parts decoration. They are essential for filling in background gaps as well as adding focal highlights. The brilliance and price of a rhinestone vary depending on the material it is made from.

The three main materials are acrylic, glass, and high-grade crystal glass (such as Preciosa). Acrylic stones are very affordable, lightweight, and available in many colors, but their cut facets are slightly rounded, resulting in a subtle shine. Glass stones offer high transparency and reflect light strongly for a more brilliant look. High-grade crystal stones feature precision-cut facets that deliver a dazzling sparkle. A good rule of thumb is to use acrylic stones for practice and glass or crystal stones for your final projects.

Resin Parts (Plastic Charms & Deco Parts): Adding 3D Dimension and Charm

These are molded plastic or resin charms featuring sweet motifs like desserts, characters, flowers, and ribbons. Smooth, domed components known as cabochons also fall into this category.

The greatest appeal of resin parts is their eye-catching three-dimensional presence. They are ideal as central "star parts"—placing just one on a project instantly establishes the overall theme. Made from materials like acrylic resin or polyresin, they are lightweight and easy to handle, available in finishes ranging from matte to high-gloss coatings.

Pearl Parts: Adding Elegance and Sophistication

Pearls are invaluable when you want to create an elegant atmosphere or a classic design. In parts decoration, half-pearls (half-round pearls) with a flat back are primarily used.

Their soft, rounded shapes reflect light gently. Mixing them among the intense sparkle of rhinestones adds depth and refined elegance to your design. Quality ranges from affordable plastic pearls to silky pearls with a graceful sheen.

Metal Parts and Charms: Sharpening the Design

Made of brass or alloys, metal elements bring a mature, luxurious touch to a piece. Filigree frames and gold or silver studs are typical examples.

Inserting metal parts between stones and resin charms tightens the visual composition, giving your piece a polished look that isn't overly sweet.

V-Cut Stones and Beads: Creating Depth and Dimension

Unlike standard flat-bottom stones, V-cut stones have a pointed, diamond-like back. Spherical beads and natural stone chips are also used as decorative accents.

Because V-cut stones have a high refractive index, they produce a brilliant sparkle unmatched by flat stones. Although they cannot be glued directly onto a flat surface, pairing them with specialized bijou clay or heavy resin lets you create stunning 3D decorations.

How Back Shapes Affect Your Craft: Shapes and Precautions

When choosing parts, the shape of the back is just as important as the design and color. If you purchase parts without checking their back shape, you might end up with pieces that cannot be glued properly.

Flat Backs: The Essential Shape for Flat Surfaces

Flat backs are the foundational shape you should choose for standard parts decoration. As the name implies, the back surface is smooth and flat.

To use them, simply apply glue to a flat base—such as a phone case or mirror—and place the part on top. Because the surface contact area is large, the adhesive bond is strong, making it easy even for beginners to create durable projects that won't fall apart. When shopping, always make sure the product description notes "Flat Back."

V-Cut / Pointed Backs (Chatons): For Embedding and 3D Work

Stones with a conical, pointed back are known as V-cut stones or chatons. If you try to glue these to a flat surface with regular adhesive, they will only touch at a single point and drop off almost immediately.

These parts are designed to be set into recessed mounts or embedded into epoxy clay. If you are a beginner looking to cover a flat surface, take care not to accidentally buy V-cut stones.

Adapting Perforated Beads and Charm Loops for Decoration

Beads designed for jewelry making have thread holes, while charms feature hanging loops. You can repurpose these for decoration with a bit of adjustment. Spherical beads have very small contact points, so you can snip them in half with wire cutters or set them in a thicker layer of adhesive. For metal charms with loops, use flat-nose pliers or cutters to remove the loop, then sand the back flat before gluing.

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Understanding Sizes: Navigating Sizes Without Confusion

Many beginners get confused by sizing codes like "ss" or millimeter (mm) measurements. Choosing the wrong size can lead to frustrating mistakes, like taking forever to fill a small space or using parts that hang off the edge of your project.

Rhinestone Sizing Guide: Understanding "ss"

Rhinestones are typically measured in "ss" (stone size). A larger number indicates a larger diameter.

When decorating an entire phone case, my recommendation is to use ss10 and ss12 as your main base sizes. Use these to build the layout, then fill in the tiny remaining gaps with ss6 and ss3. This creates a dense, beautifully polished finish.

Millimeter (mm) Sizing for Resin Parts and Pearls

Resin charms, pearls, and cabochons are measured in millimeters (mm). Holding a ruler up to your base object will help you visualize the scale.

For example, when decorating a standard phone case (roughly 15 cm x 7 cm), selecting a main focal resin part around 20 mm to 35 mm (2 cm to 3.5 cm) creates great visual balance. Anything larger may interfere with daily use, while smaller pieces might lose their impact as the main feature. Complementary pearls or small flower charms in the 6 mm to 12 mm range work well to accent the central piece.

5 Key Points for Choosing Parts Without Failure

Choosing parts solely by appearance can lead to regrets during assembly or daily use. Here are five crucial points to consider.

1. Consider Compatibility with the Base Material

The material of your base object (e.g., hard plastic, flexible polypropylene, silicone, or metal) dictates the ideal weight and flexibility of the parts you should use.

Flexible materials, like soft polypropylene or silicone cases, bend when handled. Heavy glass stones or large metal parts glued to a flexible base can pop off whenever the case flexes. For soft or flexible bases, stick to lightweight acrylic stones and small resin parts. Hard plastic cases or metal surfaces, on the other hand, can easily hold heavier glass stones and metal charms.

2. Match the Item's Purpose: Daily Use vs. Display

Consider how your finished object will be used. Daily items like phone cases or keychains experience constant friction in pockets and bags. Sharp or delicate parts on everyday items can catch on fabric or chip away over time. For portable items, choose smooth cabochons, rounded shapes, and flat-back rhinestones. For decorative display items like trays or picture frames, feel free to use dramatic, dimensional pieces.

3. Balance Your Size Ratios: Focal, Secondary, and Fillers

The secret to a dynamic, attractive design is creating clear contrast in part sizes. Covering a project with parts that are all the same size results in a flat, uninspired look. When shopping, organize your materials into three layers:

Focal Parts (Large): Main resin charms or large cabochons that define the theme.
Secondary Parts (Medium): Medium pearls, metal accents, or medium stones that support the main focus.
Filler Parts (Small): Small rhinestones (ss3–ss10) and small pearls (2mm–3mm) to pack tightly into gaps.

Preparing these three size tiers gives your work professional-looking depth and balance.

4. Keep the Color Palette Cohesive

It is easy to buy parts in every color that catches your eye, but using too many colors can make your project look chaotic. A golden rule is to limit your palette to three main tones: 1 Main Color + 1 Secondary Color + 1 Accent (or Clear/White).

Examples include Pink (Main) + White (Secondary) + Aurora (Accent), or Blue (Main) + Silver (Secondary) + Crystal (Accent). Restricting your colors keeps the finished piece looking unified and sophisticated, even with many different types of parts.

5. Check the Quality of the Foil Backing

Rhinestones have a thin silver foil layer on the back to reflect light and create shine. The quality of this backing greatly influences the lifespan of your craft. On extremely low-cost stones, the foil backing may react with strong craft glue and peel off entirely, leaving the silver layer on your base while the stone itself falls away. Look for stones specified as having "aluminum foil" or "platinum foil" backing, or purchase from reputable craft suppliers to avoid this issue.

Common Beginner Mistakes and How to Fix Them

Mistake 1: Buying Only Large Parts and Having Gaps

If you only buy large, cute resin charms and big stones, you will end up with wide gaps on your base. Trying to force large parts into those spaces creates awkward overlaps and exposes the bare surface underneath.

Solution: Always purchase small filler rhinestones (ss3 to ss6) and tiny round pearls (2 mm to 3 mm) alongside your focal pieces. Tightly packing these into the empty spaces after placing your main parts ensures a seamless finish.

Mistake 2: Mixing Acrylic and Glass Rhinestones in the Background

Mixing acrylic stones with glass stones across the same background field causes uneven lighting effects. Under light, some areas will sparkle brightly while others appear dull, creating a patchy look.

Solution: Keep material types consistent within the same visual role. Decide from the start to use all glass stones for a high-shine background, or all acrylic stones for a practice piece.

Mistake 3: Clouding Coated Stones with Extra Glue

Stones with special coatings, such as Aurora Borealis (AB) or metallic plating, are striking. However, if glue spills over the front surface or if a topcoat is applied over them, the special effect disappears, leaving the stone looking like cloudy plastic.

Solution: When using coated parts, apply glue precisely to the back of the part only, keeping the top surface clean and free of coatings or overflow.

How I Would Combine Parts for High-Impact Designs

Here are two concrete examples of how I would mix and match parts for different projects.

For Smartphone Cases: Mixing Textures for Depth

When decorating a large surface like a phone case, I like to create interest by combining different textures. First, place a 3D resin rose cabochon (around 25 mm) in the center as the main feature. Around it, scatter half-pearls (8 mm and 6 mm) for a soft luster. Finally, fill every remaining gap in the background with bright crystal glass stones (ss10 and ss6).

The contrast between the matte resin, soft pearl sheen, and sharp glass sparkle creates a rich, dimensional finish that a single material could never achieve.

For Compact Mirrors and Hair Clips: Monochromatic Gradients

For smaller accessories carried in pockets or pouches, I prioritize a smooth finish using flat-back glass stones to prevent snagging, relying on color to create visual drama. For a pink theme, I choose glass stones (ss10) in three shades: Light Rose, Rose, and Fuchsia. Placing them in a smooth gradient from light to dark, with smaller accent stones along the transitions, creates a breathtaking effect on a compact surface.

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