Ocean Diamond Halter Top Crochet Pattern

This ocean diamond halter top is one of those pieces that makes people stop and ask if you made it yourself, and I just love that! A deep navy diamond mesh centre panel with bright turquoise fans nestled inside, flanked by solid cobalt ribbed side panels, all finished with a structured high collar.

We build it in modular sections: the diamond mesh centre panel first, then two mirror-image ribbed side panels, and we join everything together before adding the collar, back lacing, armhole binding and hem border. The modular construction is a gift, because you can adjust the fit as you go.

The pattern is written for sizes XS, S, M, L and XL, and the sample shown is closest to size M. This is an advanced intermediate project, so be comfortable with shaping, chain spaces, post stitches and joining techniques before you start.

Materials

• Sport weight or fine DK mercerized cotton yarn, approximately 250 to 320 meters per 100 grams: XS 520 meters total, S 570 meters, M 630 meters, L 700 meters, XL 780 meters
• Main colour (MC): cobalt blue, approximately 70% of your yardage
• Contrast colour 1 (CC1): deep navy, approximately 20% of your yardage
• Contrast colour 2 (CC2): turquoise or aqua, approximately 10% of your yardage
• 3.0mm crochet hook, for the main fabric
• 2.75mm crochet hook (optional, for borders if your edges tend to flare)
• 4 locking stitch markers
• Tapestry needle
• Scissors
• Flexible tape measure
• Rustproof blocking pins

Abbreviations

• ch: chain
• sl st: slip stitch
• sc: single crochet
• hdc: half double crochet
• dc: double crochet
• tr: treble crochet
• FPdc: front post double crochet, yarn over, insert hook from front to back to front around the post of the indicated stitch, complete as a regular dc
• BPdc: back post double crochet, yarn over, insert hook from back to front to back around the post of the indicated stitch, complete as a regular dc
• sp: space
• st/sts: stitch / stitches
• RS / WS: right side / wrong side

Special Stitches

• Rib pair: work FPdc around the next dc, then BPdc around the following dc, repeated across the row. This creates the narrow vertical cobalt ribs in the solid side panels.
• Navy stitch bar: work 2 dc together into the same chain space edge area, then 1 dc into the next anchor point. These bars outline each diamond and visually separate the mesh sections.
• Turquoise fan: in the indicated centre chain space, work (sc, ch 2, 5 dc, ch 2, sc). For a smaller fan near the collar, use 4 dc instead of 5.
• Picot: chain 3, then slip stitch into the first chain. Used sparingly on the collar scallops for a delicate finish.

Gauge & Size

• Finished sizes: XS finished bust 72cm, S 78cm, M 84cm, L 92cm, XL 101cm; body length XS 36cm, S 37cm, M 38cm, L 40cm, XL 42cm
• Construction: centre diamond mesh panel, two ribbed side panels, joined and finished with collar, back lacing, armhole binding and hem border
• Skill level: Advanced Intermediate
• Gauge: 22 dc stitches and 11 rows = 10cm / 4 inches in blocked double crochet fabric; one diamond repeat measures approximately 5.0cm wide by 5.5cm tall
• Sizing note: for the fitted look shown, choose 4 to 8cm (about 1.5 to 3 inches) of negative ease at the bust. If you fall between sizes, use the smaller centre panel count and add width to the side ribs instead

Centre Diamond Mesh Panel

The centre panel is a vertical ladder of open diamonds, worked in deep navy (CC1), with turquoise (CC2) fans inserted as you go. The bottom begins with a half diamond so your hem remains level.

Foundation chain by size: XS 31 ch, 3 full diamonds wide, 5 vertical diamonds. S 31 ch, 3 wide, 5 vertical. M 35 ch, 3 wide, 5 vertical. L 35 ch, 3 wide, 6 vertical. XL 39 ch, 4 wide, 6 vertical.

Row 1 (WS): Dc in the 4th ch from hook and in each ch across. Turn.

Row 2 (RS): Ch 3, dc in next 2 sts, [ch 3, skip 2 sts, sc in next st, ch 3, skip 2 sts, dc in next 3 sts] repeat across, ending with dc in the last 3 sts. Turn.

Row 3: Ch 3, dc in next dc, [ch 2, sc in next ch-3 sp, ch 5, sc in next ch-3 sp, ch 2, dc in the centre dc of the next 3-dc group] repeat across; dc in the final 2 edge sts. Turn.

Row 4: Ch 3, [ch 3, sc in ch-5 sp, ch 3, 3 dc in next centre anchor] repeat across, keeping 2 dc at each outer edge. Turn.

Row 5: Ch 3, dc in next st, [ch 2, sc in next ch-3 sp, ch 5, sc in next ch-3 sp, ch 2, dc in the centre dc of the 3-dc group] repeat across. Turn.

Row 6: Repeat Row 2, aligning the new open spaces over the previous row so a complete diamond is formed.

Diamond repeat: Rows 3 through 6 form one full diamond unit. Repeat these four rows until you have the number of vertical diamonds listed for your size. End after a Row 6 equivalent.

Please note that the source pattern writes these mesh rows as stitch repeats without a closing stitch total at the end of each row, so work them exactly as written and count your diamonds against the size table above.

Adding the Turquoise Fans

With RS facing, join CC2 into the central ch-5 space of the lowest complete diamond.

Work one turquoise fan (sc, ch 2, 5 dc, ch 2, sc). Fasten off neatly to the WS.

Place fans in alternating diamonds up the vertical centre line. For sizes XS, S, and M, add fans to diamonds 1, 3, and 5. For sizes L and XL, add fans to diamonds 1, 3, and 5, with an optional smaller 4-dc fan in the 6th diamond near the collar.

For the look shown in the sample, keep the side diamonds open. Only the central vertical diamonds receive turquoise fans.

Cobalt Side Panels (Make 2)

Make two mirror-image side panels in cobalt (MC). These panels are worked from the centre outward using ribbed post-stitch fabric for structure. You can either attach each panel to the centre as you work or seam them afterwards using mattress stitch.

Side panel specifications by size: XS 34 sts at the lower edge per side, approximately 15.5cm wide, armhole shaping begins Row 13. S 38 sts, approximately 17cm, Row 13. M 42 sts, approximately 19cm, Row 14. L 46 sts, approximately 21cm, Row 15. XL 52 sts, approximately 23.5cm, Row 16.

Foundation / Row 1: Chain the listed stitch count for your size plus 2. Hdc in the 3rd ch from hook and across. Turn.

Row 2: Ch 2, dc in each st across. Turn.

Row 3: Ch 2, FPdc around next dc, BPdc around next dc, across. If one stitch remains, dc in the last st. Turn.

Rows 4 onward: Repeat Row 3, maintaining the post-stitch ribs. Work straight until the panel reaches lower bust or underarm level: through Row 12 for XS, Row 13 for S, Row 13 for M, Row 14 for L, Row 15 for XL, following the armhole start row for your size in the specifications above.

Armhole shaping: at the outer armhole edge only, decrease 2 sts at the beginning of the next 2 RS rows. Then decrease 1 st at that edge on each RS row 4 (5, 6, 7, 8) times depending on your size. Keep the centre edge straight for joining to the diamond panel.

Upper side shaping: continue working in the rib pattern while decreasing 1 st at the armhole edge every other RS row until 10 (11, 12, 13, 14) sts remain at the top. These remaining stitches become your collar extension strip.

Collar extension: continue working the collar extension strip in the rib pattern until it reaches halfway around the back neck. This should measure approximately 15 (16, 17, 18, 19) cm from the top of the diamond panel. Fasten off, leaving a long tail for seaming.

Bust shaping option: for a fuller bust, add short rows before armhole shaping. Work across 70% of the side panel, turn, and work back. Then work 85%, turn, and work back. Resume full rows after that. This adds depth without widening the hem.

Joining the Panels

Block all three body sections lightly to the schematic dimensions before joining. Do not stretch the mesh aggressively.

Place one side panel beside the centre panel with RS facing up. Pin the lower edges level and align the side panel inner edge with the centre panel outer dc edge.

Using MC or CC1, seam with a flat mattress stitch. Catch one full stitch from the solid panel and the outer edge loops of the centre panel. Keep your seam tension elastic but firm.

Repeat on the opposite side.

Check that the turquoise fans run exactly down the centre front and that the lower edge lies perfectly straight. Try it on! The side panels should wrap the bust snugly while the centre mesh lies flat without bowing outward. If needed, adjust by removing or adding one rib repeat at the outer side seam.

Back Closure

This version uses a short laced opening at centre back for the cleanest fit and easiest sizing adjustments.

Along each back edge, join MC at the hem. Work 1 row sc evenly up to the armhole level.

Next row: [sc in next 3 sts, ch 2, skip 2 sts] repeat to create 5 to 7 evenly spaced lacing loops. Keep the top loop about 2cm below the collar seam.

Make a 120 to 150cm navy cord by chaining to length, then slip stitching back along the chain. Lace from bottom to top in a criss-cross pattern and tie at the upper back.

Closed back alternative: if your fitted bust circumference is correct without a lacing gap, seam the back edges from hem to 5cm below the collar and leave a short keyhole opening. Add a small button and loop closure at the upper back.

High Collar

With RS facing, pin the two collar extension strips around the neck so the back ends meet. Seam the back ends together in MC.

Join MC at centre back. Work 1 round sc evenly around the upper neckline, including the top edge of the centre diamond panel. Aim for a firm but comfortable circumference. Decrease evenly if the neckline gaps.

Round 2: Ch 2, dc in each st around; join.

Rounds 3 and 4: Ch 2, FPdc around next dc, BPdc around next dc, around; join. These ribs create the structured cobalt collar base.

Change to CC1. Round 5: Sc around, decreasing 2 to 4 sts evenly if needed so the collar stands cleanly.

Change to CC2. Round 6 (scallops): [skip 1 st, 5 dc in next st, skip 1 st, sl st in next st] around, adjusting the last repeat symmetrically.

Optional navy rim: with CC1, work sl st loosely around the top edge, placing a picot at the peak of every second scallop.

Armhole Binding

Join CC1 at the underarm.

Round 1: Sc evenly around the armhole, working approximately 2 sc per 3 row ends on straight sections. Do not overfill the curve.

Round 2: Work reverse sc (also called crab stitch) around for a narrow rope-like navy binding. Alternatively, use a firm sl st round for a flatter edge.

Repeat for the second armhole. Block both armholes to matching curves.

Hem Border

Join CC1 at the centre back lower edge.

Round 1: Sc evenly around the entire hem, placing 1 sc in each solid panel stitch and distributing sc evenly across the bottom of the centre panel so the edge becomes level.

Round 2: Ch 1, sc in each st around. Keep the round flat. Decrease one stitch at each centre panel corner if the edge waves.

Optional turquoise accent: with CC2, surface slip stitch around the top edge of Round 1, then finish Round 2 in CC1. This creates the narrow turquoise line above the navy anchor border.

Finishing & Assembly

Weave in all tails on the WS, following stitch paths for at least 4 to 5cm. Split the mercerized cotton plies once when changing direction so ends remain secure.

Wet block in cool water with a small amount of delicate wash. Roll in a towel but do not wring. Pin the centre diamonds open to consistent dimensions, pin the lower hem perfectly level and both armhole curves symmetrically. Shape the collar upright rather than flattening it. Let everything dry completely before unpinning.

Lightly steam from a distance only if needed. Avoid pressing the raised ribs or fans flat.

Tips

Block and measure one diamond repeat before beginning the full garment. Adjust your hook size up or down until your diamond measures close to 5.0cm wide by 5.5cm tall.

Need more bust width? Add 2 rib stitches to each side panel per extra 1.8cm needed. Need less? Remove 2 rib stitches from each side panel, and keep the centre diamond panel unchanged for visual balance.

Before wearing, check your checkpoints: diamonds symmetrical with straight outer edges, both side panels identical mirror images with vertical rib columns, collar standing without gaping, and a level hem that does not flare.