When I was in school I liked geometry a lot, calculating angles and things like that. Knowing that there is an exact answer can be so reassuring. Did you know that in a rhombus all sides have the same length?
Rhombus is a scarf or stole pattern with small and large rhombi. The pattern is adjustable in length and width. Only right side rows are patterned. The pattern is charted. Gauge is not crucial, use needles to obtain a desired lace effect.
Turquoise scarf used 1 skein Grignasco Cashmere 2/28 [100% cashmere; 380 yd/347 m per 25g] on 3 mm (US 2½) needles.
Gauge: 23 stitches over 10 cm in stockinette stitch. Blocked size is 145 x 25 cm (57 x 10 inches).
Grey stole used 2 skeins Knit Picks Gloss Lace [70% Merino, 30% Silk; 440 yd/402 m per 50g] on 3.75 mm (US 5) needles. Gauge: 22 stitches over 10 cm in stockinette. Blocked size is 166 x 42 cm (65 x 16 inches).