The Christiaan van der Klaauw Grand Planetarium Eccentric Silicium, ref. CKGP33SI, is a 2026 limited edition of the Dutch brand’s planetarium watch, which shows all eight planets of the Solar System orbiting the Sun in real time. The case is 316L stainless steel hardened with a carbon-diffusion treatment. It measures 44 mm in diameter and 14.9 mm thick, and it is water-resistant to 3 ATM (30 m). The dial is made from nine pieces of oxidised silicon in blue-violet tones. The planets are hand-painted with Super-LumiNova and complete their orbits in real time. In the original Grand Planetarium Eccentric, these run from 87.97 days for Mercury to 164.80 years for Neptune. Hours and minutes are shown by open-tipped eccentric hands, and the seconds by a rotating sun logo at the centre. The self-winding movement beats at 21,600 vph (3 Hz) and has a 60-hour power reserve.

The Silicium is a variant of the Grand Planetarium Eccentric, which CvdK presented in October 2024 for the brand’s 50th anniversary. According to Monochrome, that model introduced a manufacture calibre developed since 2017 with UhrTeil AG, the company founded by Andreas Strehler. Its planetarium module has 3,338 teeth, and the planets are placed on offset orbits that reproduce their eccentric paths. The 2024 versions came in platinum (CKGP2204) and rose gold (CKGP1104) with aventurine dials, priced at EUR 227,000 and EUR 208,000. The Silicium edition replaces precious metal and stone with treated steel and a silicon dial. It comes on a sailcloth-textured FKM strap with purple stitching and a steel folding buckle. It is limited to six pieces at CHF 156,800.

Specific reviews of the Silicium edition are scarce, since Watchonista’s coverage is largely descriptive. The Grand Planetarium Eccentric line was well received. Monochrome’s Brice Goulard called it one of the most impressive astronomical watches ever made and praised the achievement of fitting all eight planets on the wrist. He noted that the 44 mm size is large and the movement decoration may be too exuberant for some. WatchesBySJX, reviewing the related Meteorite edition, praised the painted planets and the comfort for a case just over 14 mm thick. It criticised the maximalist look, the somewhat ambiguous date reading and the 3 Hz beat rate. As of October 2026, the Silicium is a current limited edition of six pieces.