diamond-point
[f. diamond n. + point n.]
1. A stylus tipped with a fragment of diamond, used in engraving, etc.
| 1874 Knight Dict. Mech. I. 698/1 Wilson Lowry introduced the diamond-point into engraver's ruling-machines. 1881 Every Man his own Mechanic §569 The diamond point..is used for roughing very small and delicate work that will not bear the gouge. |
2. Railways. Usually in pl. The set of points at a diamond crossing, where two lines of rails intersect obliquely without communicating, forming a diamond or rhombic figure; in sing. one of the acute angles formed by two rails at such a crossing.
| 1881 Daily News 15 Sept. 3/2 It [a train] had to pass over a diamond point. 1890 Morning Post 24 Oct. 6/7 A North British mineral train, while crossing a set of diamond points, ran off the line. 1894 Westm. Gaz. 24 July 5/2 On reaching the diamond point the guard's van next the engine jumped the metals. |
3. attrib., as diamond-point chisel, a chisel having the corners ground off obliquely.
| 1874 Knight Dict. Mech. s.v. Chisel. |