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tokens: with black open circles. We warn the reader that we cannot rule out the presence of other binaries with no obvious s -elements and/or RV differences among our remaining 15 giants. Another stellar population that may affect the appearance of the ChMs and likely has a connection to binary stars is the blue stragglers (BSs). In particular, we consider their evolved counterparts that lie close to the RGB. In Figure 7 , we use blue symbols to represent the candidate BS stars of NGC 3201 in the CMD. The objects marked with blue asterisks are possible BSs selected on the CMD that are evolving toward the RGB phase, which clearly displays lower values in the diagram (top right panel). The BSs in GCs are tightly linked to the cluster binary populations (Knigge et al. 2009 ). The BSs in open clusters themselves have a very high binary fraction (Mathieu Geller 2009 ), and preliminary evidence suggests the same is true in NGC 3201 (Giesers et al. 2019 ). When we include the evolved BSs in the ChM (bottom panel of Figure 7 ), they populate a well-defined sequence on the blue extension of the 1G sequence. We conclude that, based on RVs and s -process element abundances, the three bluest 1G stars that we analyzed spectroscopically are binary systems. Some of them are possibly associated with the BS population of NGC 3201, as evolved BSs would contribute to the bluest extension of the 1G sequence in the ChM. Figure 7. Top panels: CMD (left) and diagram (right) of NGC 3201. Bottom panel: ChM of NGC 3201, similar to Figure 1 but extended to show the evolved BSs. In all panels, the green dots represent our analyzed spectroscopic targets, the open blue circles are the BSs, and the blue asterisks are the evolved BSs. 6.1. Noninteracting Binary Simulations To investigate the effect of noninteracting binaries formed by pairs of 1G stars, we reproduce in Figure 8 five isochrones, I1—I5, with [Fe/H] = −1.50, [ α /Fe] = 0.4, and an age of 13 Gyr from Milone et al. ( 2018 ). These isochrones are constructed with a different combination of He, C, N, and O to represent the typical chemical pattern of different stellar populations in GCs. We used the isochrone I1, which correponds to the 1G, to generate a stellar population of 1G–1G binaries that we represent with black points in Figure 8 . Figure 8. Left panels: simulated CMD, with five isochrones corresponding to different stellar populations with different He, C, N, and O. Here I1 is the isochrone corresponding to the first population; I2 has the same abundance of C, N, and O as I1 but different He; and in I3, I4, and I5, the abundances of He, C, N, and O have been varied to represent the second population chemical pattern. Right panel: location of the five different stellar simulated populations at a reference magnitude on the ChM plane. The black points are noninteracting binaries formed by pairs of I1–I1 stars. Binaries can contribute to the width of the 1G in the ChM, but only binaries with a large mass ratio ( q ≳