Emerald Diamond Lattice Mermaid Gown: Free Crochet Pattern
There is something undeniably magical about a handmade gown. When you pick up a crochet hook and a skein of emerald yarn, you are not just crafting a garment — you are building something that carries your intention, your patience, and your creativity stitch by stitch. The Emerald Diamond Lattice Mermaid Gown is one of those projects that sits at the intersection of art and wearable fashion. It turns heads, it photographs beautifully, and best of all, it is completely achievable for a crocheter with intermediate to advanced skills. This free pattern will walk you through every step, from yarn selection and gauge swatching to the final finishing touches that give this gown its breathtaking silhouette.
Whether you are making this dress for a special photoshoot, a fantasy-themed wedding, a cosplay event, or simply because you love ambitious crochet projects, this pattern is designed to be detailed enough to follow with confidence. Let’s dive in.
About This Pattern
The Emerald Diamond Lattice Mermaid Gown gets its name from three defining elements: the rich jewel-toned color, the repeating diamond lattice stitch pattern across the body and skirt, and the iconic mermaid silhouette that hugs the body from the bust down to the knee before flaring into a dramatic fishtail hem. The lattice work creates a lacy, open texture that adds visual depth and elegance without feeling heavy or bulky. When worked in a deep emerald green yarn with a subtle sheen, the diamonds catch light in a way that genuinely mimics the iridescent quality of mermaid scales.
This pattern is written for a standard size medium, with notes on how to adjust for different sizes throughout. Always swatch before you begin and adjust your hook size as needed to match gauge.
Materials You Will Need
Yarn: Approximately 1,200 to 1,600 yards of a DK weight or light worsted yarn in emerald green. A yarn with a slight sheen — such as one containing bamboo, silk, or Tencel — will give the gown that luminous, mermaid-like quality. Some excellent choices include Lion Brand Heartstrings, Paintbox Simply DK, or any bamboo-blend DK you love. If you prefer a more structured fabric, a 100% cotton DK also works beautifully.
Hook: US Size E/3.5mm and US Size F/3.75mm. You will use the smaller hook for the fitted bodice and the larger hook for the flared skirt sections to allow natural drape and movement.
Notions: Stitch markers, a yarn needle for weaving in ends, a flexible measuring tape, scissors, and optionally a lining fabric if you prefer a fully opaque garment. For the fitted mermaid bodice, a few yards of matching spandex lining fabric are recommended for modesty and structure.
Gauge with 3.5mm hook: 20 stitches and 22 rows = 4 inches in the diamond lattice stitch pattern. Always check your gauge. Gauge matters enormously for a fitted garment.
Abbreviations and Stitch Guide
Throughout this pattern, the following abbreviations are used:
ch — chain
sl st — slip stitch
sc — single crochet
hdc — half double crochet
dc — double crochet
tr — treble crochet
sk — skip
sp — space
rep — repeat
pm — place marker
RS — right side
WS — wrong side
blo — back loop only
Diamond Lattice Stitch (worked flat):
The diamond lattice is created through a combination of chain spaces and double crochet clusters that form a repeating diagonal grid. The stitch repeat is a multiple of 6 plus 3.
Row 1 (RS): Ch required number, dc in 4th ch from hook, ch 2, sk 2 ch, dc in next ch, ch 2, sk 2 ch, dc in next ch; rep from across, turn.
Row 2 (WS): Ch 5 (counts as dc + ch 2), sk first dc, dc in next dc, ch 2, dc in next dc; rep from across, ending last dc in top of turning ch, turn.
Row 3 (RS): Ch 3 (counts as dc), dc in first ch-2 sp, ch 2, dc in next dc, ch 2, dc in next ch-2 sp; rep from across, ending dc in last sp, dc in 3rd ch of turning ch, turn.
Row 4: Ch 5, dc in next dc, ch 2, dc in next dc; rep from across, turn.
Repeat rows 3 and 4 for the diamond lattice pattern. The diagonal visual effect of the diamonds emerges as the offset ch-2 spaces stack in alternating positions.
Construction Overview
The gown is worked in four main sections: the bodice, the hip panel, the mermaid body (thigh to knee), and the flared fishtail skirt. The bodice is worked flat in two pieces (front and back) and seamed at the sides. The hip panel and mermaid body are worked in joined rounds, transitioning seamlessly from the bodice. The fishtail skirt begins at the knee and is worked flat in increasing wedge panels to create the dramatic flare.
Section One: The Bodice
The bodice is designed as a fitted sweetheart or straight-across top, depending on your preference. The instructions below are for a straight-across neckline, which is classic for mermaid gown styling. For a sweetheart neckline, additional shaping notes are included at the end of this section.
Front Bodice Panel (make 1):
Using the 3.5mm hook, ch 63.
Work in the diamond lattice stitch pattern for 26 rows, or until the piece measures approximately 12 inches from the foundation chain. This length covers from the natural waist to the bust line for a standard medium torso. If you are making this for a taller frame, add additional rows in increments of 4 to maintain the stitch pattern alignment.
At the top edge of the bodice, work one row of sc across for stability.
Fasten off and weave in ends.
Back Bodice Panel (make 1):
Work identically to the front panel. The back neckline can be left as a straight edge or shaped into a deep V or open back by dividing the work at row 20 and working each side separately, decreasing 1 stitch every other row until the desired depth is reached.
Seaming the Bodice:
With RS facing out, align the front and back panels. Using the yarn needle and a length of yarn, mattress stitch the side seams, leaving the top and bottom edges open. The bottom edge will connect to the hip panel. The top edge will be finished after trying on for fit.
Optional Bodice Straps or Stays:
If you prefer added support, crochet two chain ties approximately 18 inches each, attaching one at each upper corner of the front panel and routing them around the neck or across the back to tie. Alternatively, sew ribbon stays or boning tape along the interior side seams for structure. For a strapless wearable gown, a lining is strongly recommended.
Section Two: The Hip Panel
The hip panel bridges the bodice and the narrower mermaid column, providing ease through the hips and a smooth, flattering transition. It is worked in joined rounds.
Setup Round: With RS facing, attach yarn at the right side seam at the bottom edge of the bodice. Work 1 sc in each stitch around the entire bottom edge of the bodice, joining with a sl st to form a round. Place stitch marker at the beginning of the round.
You should have approximately 120 to 126 stitches in the round, depending on your gauge and final bodice width. Adjust as needed so that the stitch count is a multiple of 6, which is required to maintain the diamond lattice pattern in the round.
Rounds 1 through 12: Work the diamond lattice stitch in the round. When working in the round, all rows become right-side rounds, and the ch-5 turning chains are replaced by sl st joins at the end of each round followed by ch 3 to begin the next.
The hip panel should measure approximately 5 to 6 inches in length. Try the gown on (or check against your measurements) and adjust the number of rounds to suit your hip length.
Section Three: The Mermaid Column
This is the section that gives the gown its defining silhouette. The mermaid column hugs closely from the low hip down to just above the knee, creating that sleek, body-skimming line. To achieve the fitted shape, you will decrease gradually across this section.
Decrease Setup: At the end of the hip panel, take note of your current stitch count. Over the next 8 rounds, decrease evenly by working sc2tog at 4 evenly spaced points per round (decreasing 4 stitches per round, 32 stitches total over 8 rounds). This draws the silhouette in toward the knee.
Continue even (no increases or decreases) in the diamond lattice pattern for another 10 to 14 rounds, or until the column measures approximately 16 to 18 inches from the start of the hip panel. This brings you to just above the knee on most frames.
The mermaid column should feel snug but not constricting. If you find the fabric too tight to move comfortably, add 2 extra rounds of even work and consider working the last 4 rounds on the larger hook.
Section Four: The Fishtail Skirt
This is where the drama happens. The fishtail skirt begins at the knee line and fans outward in dramatic panels that pool elegantly at the floor. It is worked flat in 6 wedge panels that are then seamed together.
Wedge Panel (make 6):
Using the 3.75mm hook, ch 15.
Work in the diamond lattice stitch, increasing 1 stitch at each end of every right-side row as follows: at the beginning of RS rows, work 2 dc in the first stitch; at the end of RS rows, work 2 dc in the last stitch.
Continue increasing until the panel measures 24 inches in length, or until the widest point of each wedge is approximately 18 to 20 inches across. The combination of 6 panels will create a total circumference of 108 to 120 inches at the hem — an extravagant, sweeping pool of emerald lace.
At the bottom of each wedge, work one round of scallop edging as follows: sk 2 sts, work 5 dc in next st, sk 2 sts, sl st in next st; rep from across. This scallop trim mimics the frilled edge of a mermaid fin and adds the perfect finishing touch to the gown’s hem.
Attaching the Skirt Panels:
Lay the 6 wedge panels out flat and seam them together along their long edges using mattress stitch, forming a full circle. Attach the top edge of the assembled skirt to the bottom edge of the mermaid column using a sc join round, easing as needed for even distribution.
Finishing Touches and Embellishments
The beauty of a pattern like this lies in how much you can personalize it. Here are some ideas for finishing and embellishment that elevate the gown further.
Beading: Using a fine needle and thread, stitch seed beads or small crystal beads at the intersections of the diamond lattice across the bodice and upper skirt. This catches the light in the most spectacular way under photography or event lighting.
Shell or Scale Trim: Crochet small individual shell motifs in a slightly lighter or slightly darker shade of emerald and appliqué them along the bodice neckline or at the hip transition for a true mermaid scale effect.
Lining: Cut a stretchy lining fabric to match the bodice and mermaid column. Hand-stitch it to the interior using a whip stitch along the edges. The lining makes the gown more wearable, more comfortable against the skin, and eliminates any transparency concerns.
Ribbon Tie Back: If you left the back open or shaped a deep back neckline, thread a length of satin ribbon through the last row of sc stitches along the back edges and tie it at the center. This creates a corset-like closure that is both functional and gorgeous.
Blocking: Before wearing or photographing the gown, wet block it. Submerge the finished piece in cool water, gently press out excess water without wringing, and lay flat on blocking mats. Pin the fishtail panels into their full spread and allow to dry completely. Blocking evens out the stitches, opens up the lattice pattern, and gives the entire gown a polished, professional finish. This step genuinely transforms the project.
Sizing Notes and Adjustments
This pattern is written for a size medium with the following measurements in mind: 36-inch bust, 28-inch waist, 38-inch hip, and a total gown length of approximately 58 to 60 inches from waist to hem.
For a smaller size, reduce the foundation chain by 12 stitches (a multiple of 6) for the bodice, reduce the hip panel round count by 2, and reduce the mermaid column decrease total by 12 stitches.
For a larger size, increase the foundation chain by 12 to 24 stitches, add 2 to 4 additional rounds to the hip panel, and increase the mermaid column beginning stitch count accordingly. The fishtail skirt wedges can remain the same or be widened by starting with a wider foundation chain of 21 instead of 15.
Always use your own body measurements as the guide. Take a full bust, waist, hip, and torso length measurement before beginning, and compare them to the schematic measurements throughout the pattern. Crochet fabric has inherent stretch, especially in lace patterns, so when in doubt, go slightly smaller and let the yarn do the work.
Tips for Success
Working a full-length gown is a commitment, and going in with a few practical strategies makes the process so much more enjoyable. Work in sessions rather than marathon sittings to keep tension consistent. Keep your yarn in a cloth bag or bowl to prevent it from rolling and picking up debris. Use stitch markers liberally, especially when working in the round on the hip panel and column sections. If you set the project down for several days, do a small gauge swatch before picking back up to make sure your tension has not shifted.
Photograph your progress! Projects like this are genuinely exciting as they come together, and having photos of each stage is both motivating and useful if you want to recreate the gown or share the project with others.
Final Thoughts
The Emerald Diamond Lattice Mermaid Gown is the kind of crochet project that reminds you why you fell in love with the craft in the first place. There is something deeply satisfying about watching a collection of yarn and a few basic stitches transform into something so undeniably beautiful. Every diamond in the lattice, every scallop at the hem, every flared panel of the fishtail skirt is something you made with your own hands. That is extraordinary.
This pattern is free for personal use. If you make this gown, please share your photos — there is nothing more inspiring to a fellow crocheter than seeing a finished piece out in the world, worn with joy. Tag your project, share your yarn choices, and do not hesitate to leave questions in the comments. The crochet community is one of the most generous and helpful communities in the crafting world, and every experience with a pattern like this adds to that collective knowledge.
Now pick up your hook, wind your emerald yarn, and get started. Your mermaid gown is waiting.
