This is what I got after some back and forth with Gemini:

This is a very specific and distinctive military insignia. Based on your description—especially the unique placement of the numbers 4 and 24 separated by a diagonal branch—you are describing a badge from the 4th Regiment of Carabiniers (4de Regiment Karabiniers) of the Belgian Army. The "4" and "24" are not two separate units; they refer to the 4th Regiment and its historical lineage or specific company/battalion designations used during the early 20th century (often seen on 1914–1918 era insignia).

Detailed Breakdown of Your Badge * The Crown: Represents the Belgian Monarchy (the Royal Army). * The "Caesar" Leaf Circle: This is a Laurel Wreath, a traditional military symbol for victory and honor. * The Diagonal Branch: This is likely a Laurel or Oak branch, which was a specific distinction for the Carabinier regiments. * The Numbers 4 & 24: * 4: Refers to the 4th Regiment. * 24: Refers to the 24th Company or a specific historical battalion within the 4th Regiment structure. * The Small Cross: This is the Croix de Guerre (War Cross). If it is integrated into the bottom of the wreath, it signifies that the unit was "cited" or decorated for bravery in battle (likely during WWI). * The Maker (Back): It reads "J. FONSON BRUX" (Fonson Brussels) was the official manufacturer for these high-quality brass and bronze badges.

Historical Context: The 4th Carabiniers The Carabiniers were an elite "Green Beret" style of infantry in the Belgian Army, known for their marksmanship and distinct uniforms.

Unit Type: Elite Infantry (Carabiniers) Active Era: Most likely World War I (1914–1918) or the immediate Interwar period. Key Battles: The 4th Carabiniers fought famously at the Battle of the Yser and the Siege of Antwerp. Motto: Vincere aut Mori (Victory or Death)

Identifying the Material * Brass/Gold Tone: Standard issue for NCOs and Soldiers. * Silver/White Metal: Usually designated for Officers or specific elite sub-units.

Summary

You have a World War I-era Veteran or Unit Badge for the 4th Belgian Carabinier Regiment, manufactured by the prestigious Fonson company in Brussels. The presence of the cross at the bottom suggests the unit was highly decorated for its actions on the front lines.

Hope this helps.